CN101074912A - Apparatus and method for testing cement concrete penetration performance under loading action - Google Patents

Abstract

Translated fromChinese

一种水工混凝土荷载渗透性能测试装置，包括加压装置和试件室两部分，其中的加压装置是由钢底盘、钢板、钢立柱、弹簧和螺栓帽等部件组成；试件室由套筒、上压钢垫板、下压钢垫板、球座、混凝土试件等组成；其测试步骤为，将压力试验机通过钢板对弹簧加压，达到规定压力后立即用螺栓拧紧，并撤掉压力机，此时外部压荷载就由弹簧提供；弹簧产生的压力通过钢板、球座、上压钢垫板传递到混凝土试件上；由抗渗仪产生的压力水通过进水管及小孔注入试件的内表面；给试件外表面与套筒之间的空隙中注水，使水面与溢流孔齐平后用橡皮圈盖住；收集溢流孔流入量筒中的渗透水，用推导的公式计算出混凝土试件的渗透系数，本装置结构简单，能保证荷载长期稳定，测试数据可靠。

A hydraulic concrete load permeability testing device, including two parts: a pressurizing device and a test piece room, wherein the pressurizing device is composed of steel chassis, steel plates, steel columns, springs and bolt caps; the test piece room consists of cylinder, upper pressure steel backing plate, lower pressure steel backing plate, ball seat, concrete specimen, etc.; the test procedure is to pressurize the spring through the steel plate of the pressure testing machine, and immediately tighten it with bolts when the specified pressure is reached, and remove the test piece. When the press is dropped, the external pressure load is provided by the spring; the pressure generated by the spring is transmitted to the concrete specimen through the steel plate, the ball seat, and the upper pressure steel backing plate; the pressure water generated by the impervious instrument passes through the water inlet pipe and the small hole Inject into the inner surface of the test piece; inject water into the gap between the outer surface of the test piece and the sleeve so that the water surface is flush with the overflow hole and then cover it with a rubber ring; collect the seepage water flowing into the measuring cylinder from the overflow hole, and use the derived formula The permeability coefficient of the concrete specimen is calculated. The structure of the device is simple, which can ensure the long-term stability of the load and the reliability of the test data.

Description

Translated fromChinese

水工混凝土在荷载作用下的渗透性能测试装置及测试方法Permeability test device and test method of hydraulic concrete under load

一、技术领域1. Technical field

本发明涉及一种测量水工混凝土渗透性能的测试装置，具体地说是涉及一种在持续稳定荷载作用下水工混凝土渗透性能的测试装置及其测试方法。The invention relates to a test device for measuring the permeability of hydraulic concrete, in particular to a test device and a test method for the permeability of hydraulic concrete under continuous and stable load.

二、背景技术2. Background technology

水工混凝土的一些耐久性问题，包括：氯离子侵蚀、水的渗透溶蚀、碱集料反应、碳化和钢筋锈蚀、冻融循环破坏等都与渗透性密切相关。良好的抗渗性是保证许多重要工程安全、耐久的必要条件。多年来人们对水工混凝土渗透性以及由于气液介质的渗透引起的耐久性问题已进行了研究，但大都围绕单一影响因素展开。然而，工程实际中的水工混凝土并不是在单一因素下工作的，一般都承受两种或两种以上的因素共同作用。多种因素共同作用时，对水工混凝土的损伤作用并不是各单一因素作用的简单叠加，各因素产生的交互作用使得实际服役过程中水工混凝土的破坏过程复杂化。在实际工程中，几乎所有水工混凝土都会承受不同类型的荷载作用，荷载往往引起水工混凝土中微裂缝产生和扩展，从而影响水工混凝土的渗透性。目前我国水工混凝土抗渗性试验采用的渗水高度法，即将上口径为175mm、下口径为185mm、高150mm的截头实心圆锥体混凝土试件放入渗透仪内，通过渗透仪在试件下表面加压力水，直至上表面出现渗水现象。这种方法只能评价水工混凝土在受水压力单一因素作用下的渗透性，而实际服役中的水工混凝土结构常同时承受着荷载的作用，而常规实验装置结构简单(截头圆锥形金属筒)，且不能给试件加载，因此，受实验装置的制约，对在荷载作用下水工混凝土水渗透性的研究几乎为空白。另外，用常规方法及实验装置测量水工混凝土渗透系数时，由于水工混凝土渗透性很小，要使足量的水透过水工混凝土以保证测量精度，实验常需持续很长时间。对于无荷载作用下的渗透实验，对时间是没有限制的，但对于有荷载作用的渗透实验，如果采用常用的液压式压力机作为加载装置，过长的时间不仅不能保证荷载的持续稳定，还会导致液压式压力试验机故障，缩短其使用寿命，对其损害较大。因此，采用液压式压力试验机给试件加载是不可取的。Some durability problems of hydraulic concrete, including: chloride ion erosion, water penetration and dissolution, alkali aggregate reaction, carbonation and steel corrosion, freeze-thaw cycle damage, etc. are closely related to permeability. Good impermeability is a necessary condition to ensure the safety and durability of many important projects. Over the years, people have studied the permeability of hydraulic concrete and the durability problems caused by the penetration of gas-liquid media, but most of them revolve around a single influencing factor. However, hydraulic concrete in engineering practice does not work under a single factor, and generally bears the joint action of two or more factors. When multiple factors act together, the damage to hydraulic concrete is not a simple superposition of the effects of each single factor. The interaction of various factors complicates the damage process of hydraulic concrete in the actual service process. In practical engineering, almost all hydraulic concretes will bear different types of loads, and the loads often cause the generation and expansion of micro-cracks in hydraulic concrete, thus affecting the permeability of hydraulic concrete. At present, the water seepage height method adopted in the impermeability test of hydraulic concrete in my country is to put a truncated solid cone concrete specimen with an upper diameter of 175mm, a lower diameter of 185mm, and a height of 150mm into the permeameter, and pass through the permeameter under the specimen. Pressure water is applied to the surface until water seepage occurs on the upper surface. This method can only evaluate the permeability of hydraulic concrete under the action of a single factor of water pressure, and the hydraulic concrete structure in actual service often bears the effect of load at the same time, and the structure of the conventional experimental device is simple (truncated conical metal cylinder), and the specimen cannot be loaded. Therefore, due to the constraints of the experimental device, the research on the water permeability of hydraulic concrete under load is almost blank. In addition, when using conventional methods and experimental devices to measure the hydraulic concrete permeability coefficient, due to the low permeability of hydraulic concrete, it takes a long time for the experiment to allow sufficient water to pass through the hydraulic concrete to ensure measurement accuracy. There is no limit to the time for the permeation test without load, but for the permeation test with load, if a commonly used hydraulic press is used as the loading device, too long time will not only fail to ensure the continuous stability of the load, but also It will lead to failure of the hydraulic pressure testing machine, shorten its service life, and cause great damage to it. Therefore, it is not advisable to use a hydraulic pressure testing machine to load the specimen.

三、发明内容3. Contents of the invention

本发明的目的在于针对常规试验装置不能给试件加载以及采用液压式压力试验机加载不能保证荷载持续稳定等问题，而提供了一种水工混凝土在荷载作用下的渗透性能测试装置，该装置不仅能给试件加载，而且试件所加荷载不再由常用的液压式压力机长期提供，新的加载装置能够保证荷载的长期持续稳定，避免荷载的不稳对实验结果的干扰。The purpose of the present invention is to provide a hydraulic concrete permeability test device under load, aiming at the problems that the conventional test device cannot load the test piece and that the hydraulic pressure testing machine cannot guarantee the continuous stability of the load. Not only can the test piece be loaded, but the load on the test piece is no longer provided by the commonly used hydraulic press for a long time. The new loading device can ensure the long-term continuous stability of the load and avoid the interference of the unstable load on the experimental results.

本发明的另一个目的是利用该测试装置对水工混凝土在荷载作用下渗透性能的测试方法。Another object of the present invention is to use the testing device to test the permeability performance of hydraulic concrete under load.

本发明的目的是通过以下的技术方案来实现的：将该装置设计如下：如图1和图2所示：The purpose of the present invention is achieved by the following technical solutions: the device is designed as follows: as shown in Figure 1 and Figure 2:

一种水工混凝土在荷载作用下渗透性能测试装置，其特征在于它是由加压装置及混凝土试件室两部分组成，其中加压装置由钢底盘(1)、钢立柱(2)、钢板(3)、钢板(4)、弹簧(5)、螺栓帽(6)构成，钢底盘(1)、钢板(3)和钢板(4)的四周各钻有对称的四个圆孔，将四根圆形钢立柱(2)分别穿过钢底盘(1)、钢板(3)、钢板(4)上的四个圆孔中，在钢底盘(1)与钢板(4)之间放置混凝土试件室(17)，钢板(3)与钢板(4)之间的四根钢主柱(2)上分别套上一根弹簧(5)，然后分别用螺栓帽(6)固定；混凝土试件室(17)中的圆形套筒(7)固定在钢底盘(1)上，圆筒形混凝土试件(12)放置在套筒(7)内，混凝土试件(12)的底部垫上一块下压钢垫板(9)，其顶部盖上一块上压钢垫板(8)，在上压钢垫板(8)与钢板(4)之间放置一个球座(10)。A hydraulic concrete permeability test device under load, characterized in that it is composed of a pressurizing device and a concrete specimen room, wherein the pressurizing device consists of a steel chassis (1), a steel column (2), a steel plate (3), steel plate (4), spring (5), bolt cap (6) constitute, steel chassis (1), steel plate (3) and steel plate (4) are respectively drilled with four symmetrical circular holes around, four A circular steel column (2) passes through the four circular holes on the steel chassis (1), steel plate (3) and steel plate (4), and a concrete test piece is placed between the steel chassis (1) and the steel plate (4). In the fitting room (17), a spring (5) is placed on the four steel main columns (2) between the steel plate (3) and the steel plate (4), and then fixed with bolt caps (6) respectively; the concrete test piece The circular sleeve (7) in the chamber (17) is fixed on the steel chassis (1), the cylindrical concrete specimen (12) is placed in the sleeve (7), and the bottom of the concrete specimen (12) is padded with a Press the steel backing plate (9) down, and press a steel backing plate (8) on its top cover, place a ball seat (10) between the last pressing steel backing plate (8) and the steel plate (4).

上述的测试装置，其特征在于所述的圆形钢立柱(2)的基部是座子，上部带有螺纹。The above-mentioned testing device is characterized in that the base of the circular steel column (2) is a seat, and the upper part is threaded.

上述的测试装置，其特征在于所述的圆形套筒(7)是用有机玻璃制成，并用环氧树脂胶粘固定在钢底盘(1)上，套筒(7)的一侧开有一个溢流孔(11)。Above-mentioned test device is characterized in that described circular sleeve (7) is made of plexiglass, and is glued and fixed on the steel chassis (1) with epoxy resin, and one side of sleeve (7) has An overflow hole (11).

上述的测试装置，其特征在于所述的混凝土试件(12)与套筒(7)两侧之间均留有充水空隙，并在两侧的空隙上用橡皮圈(14)盖住。The above-mentioned testing device is characterized in that there are water-filled gaps between the concrete test piece (12) and both sides of the sleeve (7), and rubber rings (14) are used to cover the gaps on both sides.

上述的测试装置，其特征在于所述的上压钢垫板(8)内开有一个小孔(15)与进水管(16)相连后再连接至抗渗仪上。The above-mentioned test device is characterized in that a small hole (15) is opened in the upper pressure steel backing plate (8) to connect with the water inlet pipe (16) and then connected to the anti-seepage meter.

该装置的工作原理及测试方法为：工作时由液压式压力试验机对弹簧加压，压力值大小则由读取压力机表盘数值来控制，到达规定压力值时立即将螺栓拧紧并撤掉压力机，此时试件所受的外部压荷载就由弹簧(5)提供。由于弹簧弹力受混凝土变形等因素的影响很小、保压性能良好并且应力损失小、不受外部断电等干扰因素的影响，故可以进行长时间的持续稳定荷载作用状态下混凝土渗透溶蚀等性能的研究。弹簧(5)产生的压力通过钢板(4)、球座(10)、上压钢垫板(8)传递作用到试件(12)上。上压钢垫板(8)上的进水管(16)接至抗渗仪，压力水由经抗渗仪提供并流经进水管(16)和上压钢垫板内部的小孔(15)作用于圆筒形试件(12)的内表面，水压由抗渗仪上的压力表调节控制。试件外表面浸在注满水的有机玻璃套筒(7)中，套筒上方用橡皮圈(14)盖住以避免水蒸发。套筒上的溢流孔(11)控制水位，用一个塑料管连接溢流孔(11)至放于低处的量筒，这样透过环型试件壁的渗透水量可以通过量筒收集。试验测试步骤如下：步骤1：液压式压力试验机通过钢板(3)对弹簧(5)加压，当到达规定压力值时立即将螺栓(6)拧紧并撤掉压力机，此时外部压荷载就由弹簧(5)提供了；步骤2：弹簧(5)产生的压力通过钢板(4)、球座(10)、上压钢垫板(8)传递作用到圆筒形混凝土试件(12)上；步骤3：抗渗仪产生压力水，将压力水通过进水管(16)及小孔(15)注入混凝土试件(12)的内表面；步骤4：给混凝土试件(12)外表面及有机玻璃套筒(7)之间空隙注水，使水面与溢流孔(11)齐平，然后用橡皮圈(14)盖住套筒(7)以避免水蒸发；步骤5：收集经套筒(7)上的溢流孔(11)流至外接的量筒中的渗透水；步骤6：利用量筒中的渗透水，用以下的推导公式换算求得混凝土的渗透系数。The working principle and testing method of the device are as follows: when working, the hydraulic pressure testing machine pressurizes the spring, and the pressure value is controlled by reading the dial value of the pressure machine. When the specified pressure value is reached, the bolt is tightened immediately and the pressure is removed. At this time, the external compressive load on the specimen is provided by the spring (5). Since the spring force is little affected by concrete deformation and other factors, the pressure holding performance is good and the stress loss is small, and it is not affected by external power failure and other interference factors, so it can perform performance such as concrete penetration and corrosion under continuous and stable load for a long time Research. The pressure generated by the spring (5) is transmitted to the test piece (12) through the steel plate (4), the ball seat (10) and the upper pressure steel backing plate (8). The water inlet pipe (16) on the upper pressure steel backing plate (8) is connected to the anti-seepage meter, and the pressure water is provided by the anti-seepage meter and flows through the water inlet pipe (16) and the small hole (15) inside the upper pressure steel backing plate Acting on the inner surface of the cylindrical test piece (12), the water pressure is regulated and controlled by the pressure gauge on the anti-seepage meter. The outer surface of the test piece is immersed in a plexiglass sleeve (7) filled with water, and the upper part of the sleeve is covered with a rubber ring (14) to prevent water from evaporating. The overflow hole (11) on the sleeve controls the water level, and a plastic tube is used to connect the overflow hole (11) to the graduated cylinder placed at a lower place, so that the amount of permeated water passing through the wall of the annular test piece can be collected by the graduated cylinder. The test steps are as follows: Step 1: The hydraulic pressure testing machine pressurizes the spring (5) through the steel plate (3), and when the specified pressure value is reached, the bolt (6) is immediately tightened and the press is removed. At this time, the external pressure load Just provided by spring (5); Step 2: the pressure that spring (5) produces passes through steel plate (4), ball seat (10), upper pressing steel backing plate (8) and transmits action to cylindrical concrete specimen (12 ); step 3: the anti-seepage instrument produces pressure water, and injects the pressure water into the inner surface of the concrete test piece (12) through the water inlet pipe (16) and the small hole (15); Fill the gap between the surface and the plexiglass sleeve (7) with water so that the water surface is flush with the overflow hole (11), and then cover the sleeve (7) with a rubber ring (14) to avoid water evaporation; step 5: collect the The overflow hole (11) on the sleeve (7) flows to the seepage water in the external measuring cylinder; Step 6: use the seepage water in the measuring cylinder to convert and obtain the permeability coefficient of concrete with the following derivation formula.

圆环型混凝土试件渗透系数计算公式：The formula for calculating the permeability coefficient of the circular concrete specimen is:

$\mathrm{<span><span>k</span>k</span>}<span><span>=</span>=</span><span><span>-</span>-</span>\frac{\mathrm{<span><span>\&mu;q</span>\&mu;q</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>ln</span>ln</span>}\frac{{\mathrm{<span><span>r</span>r</span>}}_{\mathrm{<span><span>1</span>1</span>}}}{{\mathrm{<span><span>r</span><figure-callout\; label="r"\; filenames="A20071002313900131.png"\; state="\{\{state\}\}">r</figure-callout></span>}}_{\mathrm{<span><span>2</span>2</span>}}}}{\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&pi;</span>\&pi;</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>h</span>h</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>\&Delta;h</span>\&Delta;h</span>}}$

式中：k-渗透系数(cm/s)；q-单位时间内收集的水流量(cm³/s)；r₂-环状试件的外半径(cm)；r₁-环状试件的内半径(cm)；h-环状试件的高度(cm)；Δh-水流入面和流出面间的水头差，μ-水的粘度。In the formula: k-permeability coefficient (cm/s); q-water flow collected per unit time (cm³ /s); r₂ -outer radius of the annular specimen (cm); r₁ -annular specimen Inner radius (cm); h-height of the annular test piece (cm); Δh-water head difference between the water inflow surface and the outflow surface, μ-water viscosity.

本发明解决了常规试验装置不能给试件加载，以及采用液压式压力试验机加载不能保证荷载持续稳定等问题，而本发明是以受压弹簧为荷载的压力渗透实验装置，研究持续压荷载作用对水工混凝土的水渗透性的影响，从而揭示多因素组合条件下的水工混凝土老化和病变的机理以及组合机理，其研究成果如果推广应用于实际工程，为病险水工混凝土结构的补强加固以及高混凝土坝的设计施工和运行提供源头技术支持。The invention solves the problems that the conventional test device cannot load the test piece, and the loading by the hydraulic pressure testing machine cannot ensure the continuous stability of the load. However, the present invention uses a pressure penetration experimental device loaded with a compressed spring to study the effect of continuous pressure load The impact on the water permeability of hydraulic concrete, thus revealing the mechanism of aging and disease of hydraulic concrete under the condition of multi-factor combination and the combination mechanism. Provide source technical support for the design, construction and operation of strong reinforcement and high concrete dams.

四、附图说明4. Description of drawings

下面结合附图和实施例对本发明装置作进一步说明：Below in conjunction with accompanying drawing and embodiment the device of the present invention will be further described:

图1是受荷载作用混凝土试件水渗透试验加载装置的结构示意图Figure 1 is a schematic diagram of the structure of the loading device for the water penetration test of the concrete specimen under load

图2是混凝土试件室的结构示意图Figure 2 is a schematic diagram of the structure of the concrete specimen room

附图标记：1.钢底盘，2.钢立柱，3.钢板①，4.钢板②，5.弹簧，6.螺栓帽，7.套筒，8.上压钢垫板，9.下压钢垫板，10.球座，11.溢流孔，12.混凝土试件，13.水，14.橡皮圈，15.小孔，16.进水管，17试件室。Reference signs: 1. Steel chassis, 2. Steel column, 3.Steel plate ①, 4.Steel plate ②, 5. Spring, 6. Bolt cap, 7. Sleeve, 8. Upper pressure steel backing plate, 9. Lower pressure Steel backing plate, 10. ball seat, 11. overflow hole, 12. concrete specimen, 13. water, 14. rubber ring, 15. small hole, 16. water inlet pipe, 17 specimen chamber.

五、具体实施方式5. Specific implementation

实施例1  水工混凝土在荷载作用下的渗透性能测试装置Example 1 Permeability test device for hydraulic concrete under load

该测试装置由加压装置和试件室(17)两部分组成，其中加压装置中的钢底盘(1)、钢板(3)和钢板(4)，分别为长340mm，宽170mm，高28mm，在其四周各钻有4个对称的直径为18mm的圆孔，将四根长650mm，直径为16mm下端有直径为25mm的座子，上端带有螺纹的钢立柱(2)，穿入钢底盘(1)上的四个圆孔中，钢底盘(1)上放置试件室(17)，它是由直径为130mm，高120mm，厚8mm的有机玻璃套筒(7)放置在钢底盘(1)上，把内外直径分别为30mm和110mm，高110mm的混凝土试件(12)放入套筒(7)中，试件(12)得底部有一块直径110mm，高10mm的下压钢垫板(9)，试件(12)的上部放置一块直径为120mm，高18mm的上压钢垫板(8)，在钢垫板(8)上面再放置一个直径为35mm的球座(10)；再将钢板(4)通过四个圆孔套入钢立柱(2)上，使钢板(4)与球座(10)紧密相接，并在四根钢立柱(2)上分别套上直径为3mm，高450mm的弹簧(5)，然后将钢板(3)从四个圆孔中套在四根钢立柱(2)上，最后用螺栓帽(6)拧紧固定钢板(3)，上压钢垫板(8)内钻有一个小圆孔(15)，并与进水管(16)相连接后再接置抗渗仪上，在混凝土试件(12)与套筒(7)之间充水(13)，并使水面与溢流孔(11)齐平，充水后套筒(7)上方用橡皮圈(14)盖住，溢流孔(11)通过橡皮管连接量筒，积留从溢流孔(11)流出的渗漏水，根据渗漏水量用渗透系数计算公式(3)求出渗漏系数值。The test device consists of two parts: a pressurizing device and a specimen chamber (17), wherein the steel chassis (1), steel plate (3) and steel plate (4) in the pressurizing device are respectively 340mm long, 170mm wide and 28mm high , four symmetrical round holes with a diameter of 18mm are respectively drilled around it, and four steel columns (2) with a diameter of 25mm at the lower end of 650mm in length and 16mm in diameter and threaded on the upper end are inserted into the steel columns (2). In the four circular holes on the chassis (1), the specimen chamber (17) is placed on the steel chassis (1), which is placed on the steel chassis by a plexiglass sleeve (7) with a diameter of 130 mm, a height of 120 mm, and a thickness of 8 mm. (1), put the concrete test piece (12) with inner and outer diameters of 30mm and 110mm and a height of 110mm into the sleeve (7), and the bottom of the test piece (12) has a piece of pressing steel with a diameter of 110mm and a height of 10mm Backing plate (9), place a diameter 120mm on the top of test piece (12), press steel backing plate (8) of height 18mm, place a ball seat (10mm) that diameter is 35mm again on steel backing plate (8). ); then put the steel plate (4) into the steel column (2) through four round holes, so that the steel plate (4) and the ball seat (10) are closely connected, and put the steel plate (4) on the four steel columns (2) respectively A spring (5) with a diameter of 3mm and a height of 450mm, then put the steel plate (3) on the four steel columns (2) through the four round holes, and finally tighten the steel plate (3) with the bolt cap (6), and put it on A small round hole (15) is drilled in the pressure steel backing plate (8), and is connected to the water inlet pipe (16) and then connected to the anti-seepage meter. Between the concrete test piece (12) and the sleeve (7) Fill water (13) between them, and make the water surface flush with the overflow hole (11). After filling the water, cover the top of the sleeve (7) with a rubber ring (14). Accumulate the seepage water flowing out from the overflow hole (11), and obtain the seepage coefficient value with the seepage coefficient calculation formula (3) according to the seepage water amount.

实施例2  对水工混凝土荷载渗透系数的测试方法。Example 2 Test method for load permeability coefficient of hydraulic concrete.

1、原材料与试件1. Raw materials and test pieces

用P·O32.5级水泥(物理性能见表1)，II级粉煤灰，细度模数为2.5的河砂，最大粒径10mm的石灰岩人工碎石及自来水按表2所示配合比配制混凝土，成型成内、外直径分别为30mm和110mm的圆筒形试件，每组试样6个。试件在混凝土标准养护室养护28d后，用金刚石锯片将试件两头截去，得到高度为110mm的试件。每组试件中取3个测定抗压强度，作为其余试件进行抗渗实验时加荷大小的参考。各组试件的抗压强度见表2。Use P O32.5 grade cement (see Table 1 for physical properties), II grade fly ash, river sand with a fineness modulus of 2.5, limestone artificial gravel with a maximum particle size of 10mm and tap water according to the mix ratio shown in Table 2 Concrete was prepared and formed into cylindrical specimens with inner and outer diameters of 30mm and 110mm respectively, with 6 specimens in each group. After the specimen was cured in the concrete standard curing room for 28 days, the two ends of the specimen were cut off with a diamond saw blade to obtain a specimen with a height of 110 mm. Three specimens in each group were selected to measure the compressive strength, which was used as a reference for the loading size of the remaining specimens in the impermeability test. The compressive strength of each group of specimens is shown in Table 2.

                     表1  水泥的基本物理性能   比表面积/m²/kg     凝结时间/min      抗压强度/MPa       抗折强度/MPa   初凝   终凝   3d   28d   3d   28d     305   185   240   4.6   8.7   19.2   41.2Table 1 Basic physical properties of cement Specific surface area/m² /kg Coagulation time/min Compressive strength/MPa Flexural strength/MPa initial setting final set 3d 28d 3d 28d 305 185 240 4.6 8.7 19.2 41.2

               表2  混凝土试件配合比和抗压强度   试件组               混凝土配合比/kg/m³   抗压强度f_c/MPa水泥  粉煤灰砂碎石水FDN   Cs1Cs2Cs3   192234290   485972   652636611   132412871241   175175175   1.201.471.81     19.825.430.1Table 2 Mix ratio and compressive strength of concrete specimens Specimen group Concrete mix ratio/kg/m³ Compressive strength f_c /MPa cement fly ash sand gravel water FDN Cs1Cs2Cs3 192234290 485972 652636611 132412871241 175175175 1.201.471.81 19.825.430.1

2、试验步骤2. Test steps

每组试件取2个分别进行试验。Take 2 specimens from each group to test separately.

步骤1：试验时将内、外直径分别为30mm和110mm、高110mm的圆筒形混凝土试件(12)先用环氧树脂砂浆粘贴在直径为120mm、高18mm上压钢垫板(8)和直径为110mm、高10mm下压钢垫板(9)上，待环氧树脂硬化后放入真空吸水仪抽真空3h，随后吸入自来水并保持真空1h，关闭真空吸水仪让试件吸水18h，以便在试验时尽快达到渗流稳定。Step 1: During the test, the cylindrical concrete specimen (12) with the inner and outer diameters of 30mm and 110mm respectively and a height of 110mm is first pasted on the steel backing plate (8) with a diameter of 120mm and a height of 18mm with epoxy resin mortar Press down on the steel backing plate (9) with a diameter of 110 mm and a height of 10 mm. After the epoxy resin is hardened, put it into a vacuum water absorber to evacuate for 3 hours, then inhale tap water and keep the vacuum for 1 hour. Turn off the vacuum water absorber and let the specimen absorb water for 18 hours In order to achieve seepage stability as soon as possible during the test.

步骤2：将预处理过的试件在0.8MPa的水压下渗流至出水流量基本稳定。Step 2: Seep the pretreated specimen under a water pressure of 0.8MPa until the outlet flow is basically stable.

步骤3：确定初次施加荷载的大小f。初次施加荷载f为试件的抗压强度f_c的0.1倍，即应力比η(η＝f/f_c)为0.1。Step 3: Determine the size f of the initial load. The initial applied load f is 0.1 times the compressive strength f_c of the specimen, that is, the stress ratio η (η=f/f_c ) is 0.1.

步骤4：液压式压力试验机通过长340mm、宽170mm、高28mm的钢板(3)对直径为3mm、高450mm的弹簧(5)加压，当到达规定压力值f时立即将螺栓(6)拧紧并撤掉压力机，此时外部压荷载就由弹簧(5)提供。弹簧(5)产生的压力通过长340mm、宽170mm、高20mm的钢板(4)、高35mm的球座(10)、上压钢垫板(8)传递作用到试件(12)上。Step 4: The hydraulic pressure testing machine pressurizes the spring (5) with a diameter of 3 mm and a height of 450 mm through a steel plate (3) with a length of 340 mm, a width of 170 mm, and a height of 28 mm. When the specified pressure value f is reached, the bolt (6) Tighten and remove the press, and the external pressure load is provided by the spring (5). The pressure produced by the spring (5) is transferred to the test piece (12) through the steel plate (4) with a length of 340 mm, a width of 170 mm, and a height of 20 mm, a ball seat (10) with a height of 35 mm, and an upper pressing steel backing plate (8).

步骤5：抗渗仪产生0.8MPa的压力水，将压力水通过内径为5mm的进水管(16)及直径为5mm的小孔(15)注入试件(12)的内表面。Step 5: The anti-seepage instrument generates pressure water of 0.8 MPa, and injects the pressure water into the inner surface of the test piece (12) through the water inlet pipe (16) with an inner diameter of 5 mm and the small hole (15) with a diameter of 5 mm.

步骤6：给试件(12)外表面与外径为138mm、厚4mm的有机玻璃套筒(7)之间注水，并用橡皮圈(14)盖住套筒(7)以避免水蒸发。Step 6: Fill water between the outer surface of the test piece (12) and the plexiglass sleeve (7) with an outer diameter of 138 mm and a thickness of 4 mm, and cover the sleeve (7) with a rubber ring (14) to avoid water evaporation.

步骤7：当渗流持续时间为7～10h后，收集经套筒(7)上的内径为4mm溢流孔(11)流至外接的量筒中的渗透水，并用精度为0.1g的电子秤计量。记录渗透水的重量、压力f的大小、渗流持续时间。Step 7: When the seepage lasts for 7 to 10 hours, collect the seepage water flowing into the external measuring cylinder through the overflow hole (11) with an inner diameter of 4mm on the sleeve (7), and measure it with an electronic scale with an accuracy of 0.1g . Record the weight of permeated water, the magnitude of pressure f, and the duration of seepage.

步骤8：增加荷载f，重复步骤4～步骤7。荷载增量由η控制，每次η增大0.1，直至η达到0.8为止(η＝0.1，0.2，...，0.8)，因此，每个试件可得到8组试验结果。Step 8: Increase the load f, and repeat steps 4 to 7. The load increment is controlled by η, each time η increases by 0.1 until η reaches 0.8 (η = 0.1, 0.2, ..., 0.8), therefore, 8 sets of test results can be obtained for each specimen.

步骤9：对其它试件重复步骤1～步骤8，直至完成全部的6个试件的试验工作。Step 9: Repeat steps 1 to 8 for other specimens until the test work of all 6 specimens is completed.

3、试验结果3. Test results

(1)渗透系数计算公式的推导(1) Derivation of the formula for calculating the permeability coefficient

混凝土的渗透系数根据达西定律计算，即The permeability coefficient of concrete is calculated according to Darcy's law, that is,

$\mathrm{<span><span>q</span>q</span>}<span><span>=</span>=</span>\mathrm{<span><span>k</span>k</span>}\frac{\mathrm{<span><span>\&mu;S\&Delta;h</span>\&mu;S\&Delta;h</span>}}{\mathrm{<span><span>L</span>L</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>1</span>1</span>}<span><span>)</span>)</span>$

式中：q-单位时间内的流量(cm³/s)；k-渗透系数(cm/s)；S-过水面积(cm²)；Δh-水的流入面和流出面间的水头差(cm)；L-渗透距离(cm)；μ-水的粘度。In the formula: q-flow per unit time (cm³ /s); k-permeability coefficient (cm/s); S-passing area (cm² ); Δh-water head difference between the inflow surface and the outflow surface (cm); L-penetration distance (cm); μ-viscosity of water.

达西公式要求孔隙平行不发生横向渗透，对混凝土内部孔结构复杂且不断变化的材料是难以做到的，但目前国内外学者认为达西定律对于水泥混凝土还是适用的。对圆环形试件假设仅发生径向渗透，当流量q一定时，在半径为r，厚度为Δr的薄壁两边的水压差Δh_r为Darcy's formula requires parallel pores without lateral penetration, which is difficult for materials with complex and constantly changing pore structures inside concrete. However, scholars at home and abroad believe that Darcy's law is still applicable to cement concrete. Assuming that only radial permeation occurs for the annular specimen, when the flow rate q is constant, the water pressure difference Δh_r on both sides of the thin wall with radius r and thickness Δr is

$\mathrm{<span><span>\&Delta;</span>\&Delta;</span>}{\mathrm{<span><span>h</span>h</span>}}_{\mathrm{<span><span>r</span>r</span>}}<span><span>=</span>=</span>\frac{\mathrm{<span><span>q\&Delta;r</span>q\&Delta;r</span>}}{\mathrm{<span><span>k\&mu;</span>k\&mu;</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&pi;r</span>\&pi;r</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>h</span>h</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}<span><span>)</span>)</span>$

对式(2)两边作积分Integrate both sides of equation (2)

$\mathrm{<span><span>q</span>q</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>{<span><span>\&Integral;</span>\&Integral;</span>}_{{\mathrm{<span><span>r</span>r</span>}}_{\mathrm{<span><span>1</span>1</span>}}}^{{\mathrm{<span><span>r</span><figure-callout\; label="r"\; filenames="A20071002313900131.png"\; state="\{\{state\}\}">r</figure-callout></span>}}_{\mathrm{<span><span>2</span>2</span>}}}\frac{\mathrm{<span><span>dr</span>dr</span>}}{\mathrm{<span><span>r</span>r</span>}}<span><span>=</span>=</span>\mathrm{<span><span>k\&mu;</span>k\&mu;</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&pi;</span>\&pi;</span>}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\mathrm{<span><span>h</span>h</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>{<span><span>\&Integral;</span>\&Integral;</span>}_{{\mathrm{<span><span>h</span>h</span>}}_{\mathrm{<span><span>1</span>1</span>}}}^{{\mathrm{<span><span>h</span><figure-callout\; label="h"\; filenames="A20071002313900131.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span><span>2</span>2</span>}}}\mathrm{<span><span>dh</span>d\; h</span>}$

可得圆环型试件渗透系数计算公式The formula for calculating the permeability coefficient of the ring-shaped specimen can be obtained

$\mathrm{<span><span>k</span>k</span>}<span><span>=</span>=</span><span><span>-</span>-</span>\frac{\mathrm{<span><span>\&mu;q</span>\&mu;q</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>ln</span>ln</span>}\frac{{\mathrm{<span><span>r</span>r</span>}}_{\mathrm{<span><span>1</span>1</span>}}}{{\mathrm{<span><span>r</span><figure-callout\; label="r"\; filenames="A20071002313900131.png"\; state="\{\{state\}\}">r</figure-callout></span>}}_{\mathrm{<span><span>2</span>2</span>}}}}{\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&pi;</span>\&pi;</span>}<span><span>\&CenterDot;</span>\&Center\; Dot;</span>\mathrm{<span><span>h</span>h</span>}<span><span>\&CenterDot;</span>\&CenterDot;</span>\mathrm{<span><span>\&Delta;h</span>\&Delta;h</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>3</span>3</span>}<span><span>)</span>)</span>$

式中：k-渗透系数(cm/s)；q-单位时间内收集的水流量(cm³/s)；r₂-环状试件的外半径(cm)；r₁-环状试件的内半径(cm)；h-环状试件的高度(cm)；Δh-水流入面和流出面间的水头差，本实验中即为砂浆渗透仪压力表读数；μ-水的粘度。In the formula: k-permeability coefficient (cm/s); q-water flow collected per unit time (cm³ /s); r₂ -outer radius of the annular specimen (cm); r₁ -annular specimen h-the height of the annular specimen (cm); Δh-the water head difference between the water inflow surface and the outflow surface, which is the reading of the mortar osmometer pressure gauge in this experiment; μ-the viscosity of water.

(2)荷载对混凝土渗透性的影响(2) The effect of load on the permeability of concrete

         表3  不同应力比下混凝土试件的渗透系数k/10^-10cm.s^-1   η   Cs11   Cs12   Cs21   Cs22   Cs31   Cs32   0.10.20.30.40.50.60.70.8   10.029.447.406.375.825.214.8517.88   8.026.755.014.023.563.108.2819.95   40.0636.2329.2226.4922.1423.0738.6471.61   54.1949.0336.1129.5628.1524.3251.6077.33   21.2419.2614.8811.8210.4310.7121.63131.60   15.7014.2511.979.838.868.4516.6330.333Table 3 The permeability coefficient k/10^-10 cm.s^-1 of concrete specimens under different stress ratios n Cs11 Cs12 Cs21 Cs22 Cs31 Cs32 0.10.20.30.40.50.60.70.8 10.029.447.406.375.825.214.8517.88 8.026.755.014.023.563.108.2819.95 40.0636.2329.2226.4922.1423.0738.6471.61 54.1949.0336.1129.5628.1524.3251.6077.33 21.2419.2614.8811.8210.4310.7121.63131.60 15.7014.2511.979.838.868.4516.6330.333

表3分别为不同配合比、不同强度混凝土试件的渗透系数k随应力比η的变化。由表3看出：Table 3 shows the variation of the permeability coefficient k of concrete specimens with different mix ratios and different strengths with the stress ratio η. It can be seen from Table 3:

①混凝土试件的渗透性与抗压强度密切相关，强度越高，渗透系数越小。强度高的混凝土试件，不仅由于成型水灰比较低，水泥浆体结构较致密，而且由于单位体积集料用量较少，因此集料-水泥浆体界面较少。然而，集料-水泥浆体界面处的过渡区是混凝土中的薄弱部位，容易成为水渗透的通道，在受应力作用时也容易引发裂缝的生成和扩展。① The permeability of concrete specimens is closely related to the compressive strength, the higher the strength, the smaller the permeability coefficient. Concrete specimens with high strength not only have a denser cement paste structure due to the lower forming water-cement ratio, but also have less aggregate-cement paste interface due to less aggregate per unit volume. However, the transition zone at the aggregate-cement paste interface is a weak part in concrete, which is easy to become a channel for water penetration, and it is also easy to cause cracks to form and expand under stress.

②各试件的渗透系数随应力比的变化规律基本相同。当应力比小于0.3时，各试件的渗透系数随应力比增大而逐渐减小，除个别试件外，大约在应力比为0.6左右渗透系数达到最小。当应力比超过0.6后，渗透系数突然增大。②The variation law of permeability coefficient with stress ratio of each specimen is basically the same. When the stress ratio is less than 0.3, the permeability coefficient of each specimen decreases gradually with the increase of the stress ratio. Except for a few specimens, the permeability coefficient reaches the minimum around the stress ratio of 0.6. When the stress ratio exceeds 0.6, the permeability coefficient increases suddenly.

究其原因，应力引起的混凝土渗透性的变化显然与结构变化、尤其是水泥浆体—集料界面和裂缝状态的变化有关。在试件所受到的是轴向压力，荷载方向与水的渗流方向垂直。压力对混凝土中裂缝状态和渗透性有相反的两个作用：在一定范围内，压力将引起混凝土中与荷载方向平行、或者说与荷载方向偏差较小的原生裂缝的扩展及新生裂缝的形成，导致混凝土渗透性的增大；而另一方面，压力方向垂直于原生裂缝则在一定程度上被“压合”，使得混凝土渗透性的降低。因此，压力对混凝土渗透性的影响是这两种作用的综合效应。值得注意的是，本实验中所用混凝土试件是圆筒状试件，受压荷载作用时，试件轴向变形导致被“压合”裂缝(严格讲应该为“裂面”)是与水的渗流方向平行，而径向变形产生的裂缝(裂面)则多数与水的渗流方向垂直，这两类裂缝对混凝土渗透系数的影响程度是有较大差异。The reason is that the change of concrete permeability caused by stress is obviously related to the structural change, especially the change of cement paste-aggregate interface and crack state. The specimen is subjected to axial pressure, and the load direction is perpendicular to the seepage direction of water. The pressure has two opposite effects on the crack state and permeability in concrete: within a certain range, the pressure will cause the expansion of the original cracks in the concrete parallel to the load direction, or the deviation from the load direction is small, and the formation of new cracks. It leads to the increase of concrete permeability; on the other hand, the pressure direction perpendicular to the original cracks is "compressed" to a certain extent, which reduces the concrete permeability. Therefore, the effect of pressure on the permeability of concrete is the combined effect of these two effects. It is worth noting that the concrete specimen used in this experiment is a cylindrical specimen. When the compressive load is applied, the axial deformation of the specimen will cause the "compressed" crack (strictly speaking, it should be "cracked surface") to be in contact with the water. The seepage direction of the concrete is parallel to that of the concrete, while the cracks (crack surfaces) produced by radial deformation are mostly perpendicular to the seepage direction of the water. There is a big difference in the degree of influence of these two types of cracks on the concrete permeability coefficient.

③由于以上两种效应，混凝土在所受压应力f低于30％极限应力f_c时，其中的集料—水泥浆体界面缝是稳定的，不会扩展。当f达到30～50％f_c时，界面缝将在过渡区内缓慢扩展。当f超过f_c的50％时，裂缝扩展就可以延伸到水泥基材中。而当f超过f_c的75％时，水泥基材中的裂缝也会不停扩展，最终导致混凝土破坏。本实验中混凝土试件在应力比为0.1～0.2时，渗透系数略有降低但变化较小。而当应力比0.3时候，渗透系数会突然变小，这是压应力使得混凝土内部的一些原始微裂缝闭合所致，而此时应力还不能使骨料与水泥浆体界面产生裂缝。当应力比增加到0.3～0.6时，渗透系数继续减小，从理论上讲，此时荷载已足以引起裂缝的扩展，因此渗透系数的继续减小说明此时裂缝的扩展和形成对混凝土渗透性的增大效应仍小于与于水渗流方向平行的裂缝“压合”对渗透性的降低效应。应力比进一步增加到0.6时，渗透系数转为增大，这是因为骨料与水泥浆体界面裂缝不断产生新裂缝并开始扩展。当应力达0.7和0.8时候渗透系数呈显著增加。按照混凝土中裂缝产生扩展规律，这时试件中的砂浆部分也开始产生裂缝，并不断发展与毛细孔等渗水通道相互联结，裂缝扩展对渗透性的影响已大大超过了裂缝“压合”的影响。③ Due to the above two effects, when the compressive stress f of the concrete is lower than 30% of the ultimate stress f_c , the aggregate-cement paste interface joints are stable and will not expand. When f reaches 30-50% f_c , the interface seam will expand slowly in the transition zone. When f exceeds 50% of_fc , crack propagation can extend into the cement matrix. And when f exceeds 75% of_fc , the cracks in the cement substrate will continue to expand, eventually leading to concrete failure. In this experiment, when the stress ratio of concrete specimens is 0.1-0.2, the permeability coefficient decreases slightly but the change is small. When the stress ratio is 0.3, the permeability coefficient will suddenly decrease, which is caused by the closure of some original micro-cracks inside the concrete due to the compressive stress, but at this time the stress cannot cause cracks at the interface between the aggregate and the cement paste. When the stress ratio increases to 0.3-0.6, the permeability coefficient continues to decrease. Theoretically speaking, the load at this time is enough to cause the expansion of cracks, so the continuous decrease of the permeability coefficient shows that the expansion and formation of cracks at this time have a great impact on the permeability of concrete. The increase effect of the fracture is still smaller than the reduction effect of the fracture "compression" parallel to the water seepage direction on the permeability. When the stress ratio is further increased to 0.6, the permeability coefficient turns to increase, because the cracks at the interface between aggregate and cement paste continuously generate new cracks and start to expand. The permeability coefficient increases significantly when the stress reaches 0.7 and 0.8. According to the law of crack generation and expansion in concrete, at this time, the mortar part of the test piece also began to produce cracks, and continued to develop and connect with capillary pores and other seepage channels. The impact of crack expansion on permeability has greatly exceeded the "compression" of cracks. Influence.

(3)渗透系数与应力比及混凝土强度的关系(3) Relationship between permeability coefficient, stress ratio and concrete strength

根据本实验结果，当应力比小于0.6时，渗透系数随着应力比的增加而减小，渗透系数随着应力比的变化趋势看，两者近似呈负指数函数关系。因此，对表3中各组试件(每组2个)实验数据按下式进行拟合：According to the experimental results, when the stress ratio is less than 0.6, the permeability coefficient decreases with the increase of the stress ratio, and the relationship between the permeability coefficient and the stress ratio is approximately negative exponential function. Therefore, the experimental data of each group of specimens (2 in each group) in Table 3 are fitted according to the following formula:

                       k＝k₀e^-aη             (4)k＝k₀ e^-aη (4)

式中：k-不同应力比η(η≤0.6)时混凝土的渗透系数(10^-10cm/s)；k₀和a-回归系数，其中k₀的物理意义也就是无应力状态下混凝土的渗透系数(10^-10cm/s)。In the formula: k-the permeability coefficient_ofconcrete (^10-10 cm/s) when different stress ratios η (η≤0.6); Permeability coefficient (10^-10 cm/s).

由式(4)拟合的结果(k₀、a)见表4。The results (k₀ , a) fitted by formula (4) are shown in Table 4.

      表4  表3中实验数据按式(4)拟合结果     试件  k₀   a   R²     Cs1Cs2Cs3  54.8621.0210.68   1.4751.3771.482   0.7890.7580.736Table 4 Fitting results of the experimental data in Table 3 according to formula (4) Specimen k₀ a R² Cs1Cs2Cs3 54.8621.0210.68 1.4751.3771.482 0.7890.7580.736

从表4看出：It can be seen from Table 4:

①渗透系数与应力比密切相关。这样利用式(4)只需试验得出没有外部应力作用下试件的平均渗透系数，便能估算在一定应力比(小于0.6)下该组试件的渗透系数了。①The permeability coefficient is closely related to the stress ratio. In this way, using formula (4), only the average permeability coefficient of the specimens without external stress can be obtained through experiments, and the permeability coefficient of the group of specimens under a certain stress ratio (less than 0.6) can be estimated.

②混凝土试件的渗透性与抗压强度密切相关，强度越高，渗透系数越小。从表4的拟合结果也可以看，抗压强度不同的各组试件的拟合参数中，a的值相差不大，即压力对不同强度混凝土的渗透性的影响基本相同。不同抗压强度试件k₀值相差较大，说明无应力状态下混凝土的渗透系数与抗压强度密切相关。② The permeability of concrete specimens is closely related to the compressive strength, the higher the strength, the smaller the permeability coefficient. It can also be seen from the fitting results in Table 4 that among the fitting parameters of different groups of specimens with different compressive strengths, the value of a has little difference, that is, the influence of pressure on the permeability of concrete with different strengths is basically the same. The k₀ values of specimens with different compressive strengths are quite different, indicating that the permeability coefficient of concrete in the unstressed state is closely related to the compressive strength.

根据表4中结果，用下式对kf_c⁴～η关系进行拟合：According to the results in Table 4, use the following formula to fit the relationship between kf_c⁴ ~η:

${\mathrm{<span><span>kf</span>kf</span>}}_{\mathrm{<span><span>c</span>c</span>}}^{\mathrm{<span><span>4</span>4</span>}}<span><span>=</span>=</span>{\mathrm{<span><span>k</span>k</span>}}_{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>e</span>e</span>}}^{<span><span>-</span>-</span>{\mathrm{<span><span>a</span>a</span>}}_{\mathrm{<span><span>1</span>1</span>}}\mathrm{<span><span>\&eta;</span>\&eta;</span>}}<span><span>-</span>-</span><span><span>-</span>-</span><span><span>-</span>-</span><span><span>(</span>(</span>\mathrm{<span><span>5</span>5</span>}<span><span>)</span>)</span>$

其中k的单位为10^-10cm/s，f_c的单位为MPa。拟合结果为：k₁＝8.694×10⁶，a₁＝1.4425，复相关系数R＝0.865。Among them, the unit of k is 10^-10 cm/s, and the unit of f_c is MPa. The fitting results are: k₁ =8.694×10⁶ , a₁ =1.4425, complex correlation coefficient R=0.865.

从拟合结果可以看出，各组试件按式(5)和式(4)拟合结果无明显差别。比较式(5)和式(4)，实际上可以看作$k_0=k{f}_c^{-4},$即无应力状态下混凝土的渗透系数与抗压强度4次方得倒数成正比。根据式(5)可以在相似条件下，制备的不同强度混凝土在不同压荷载的条件下的渗透系数，估算某一强度混凝土在相应压荷载下的渗透系数。It can be seen from the fitting results that there is no significant difference in the fitting results of each group of specimens according to formula (5) and formula (4). Comparing formula (5) and formula (4), it can actually be seen as$k_0=k{f}_c^{-4},$ That is, the permeability coefficient of concrete in the unstressed state is proportional to the reciprocal of the fourth power of the compressive strength. According to formula (5), the permeability coefficient of concrete with different strengths under different compressive loads can be prepared under similar conditions, and the permeability coefficient of a certain strength concrete under corresponding compressive loads can be estimated.

综上分析，压荷载的存在会影响混凝土的渗透性。当压应力低于60％极限应力时，压力使得混凝土与荷载方向垂直的原生裂缝则在一定程度上被“压合”，使得混凝土的渗透系数随应力比的增大而近似呈负指数函数减小。压应力达到70％极限应力后，荷载引起的裂缝扩展对渗透性的影响已超过了裂缝“压合”的影响，混凝土的渗透性随应力比的增大而显著增大。混凝土的渗透系数与其抗压强度4次方的倒数存在密切的相关性。Based on the above analysis, the existence of compressive load will affect the permeability of concrete. When the compressive stress is lower than 60% of the ultimate stress, the pressure makes the original cracks in the concrete perpendicular to the load direction be "compressed" to a certain extent, so that the permeability coefficient of the concrete decreases approximately with a negative exponential function as the stress ratio increases. Small. After the compressive stress reaches 70% of the ultimate stress, the influence of the crack expansion caused by the load on the permeability has exceeded the influence of the crack "compression", and the permeability of the concrete increases significantly with the increase of the stress ratio. The permeability coefficient of concrete is closely related to the reciprocal of the fourth power of its compressive strength.

Claims (6)

1. a concrete for hydraulic structure oozes saturating performance testing device under the effect at load, it is characterized in that it is made up of pressue device and concrete sample chamber two parts, wherein pressue device is by steel bottom plate (1), steel column (2), steel plate (3), steel plate (4), spring (5), nuts (6) constitutes, steel bottom plate (1), respectively be drilled with four circular holes of symmetry around steel plate (3) and the steel plate (4), four circular steel columns (2) are passed steel bottom plate (1) respectively, steel plate (3), in four circular holes on the steel plate (4), between steel bottom plate (1) and steel plate (4), place concrete sample chamber (17), put a spring (5) respectively on four steel principal posts (2) between steel plate (3) and the steel plate (4), use nuts (6) fixing then respectively; Circular sleeve (7) in the concrete sample chamber (17) is fixed on the steel bottom plate (1), cylindrical shape concrete sample (12) is placed in the sleeve (7), the bottom pad lastblock of concrete sample (12) presses down billet (9), compressed steel backing plate (8) on its top cover lastblock is placed a ball seat (10) between last compressed steel backing plate (8) and steel plate (4).

2. proving installation according to claim 1 is characterized in that the base portion of described circular steel column (2) is a stand, and top is threaded.

3. proving installation according to claim 1 is characterized in that described circular sleeve (7) is to make with organic glass, and is adhesively fixed with epoxy resin and fixes on the steel bottom plate (1), and a side of sleeve (7) has a spout hole (11).

4. proving installation according to claim 1 is characterized in that all leaving the water-filling space between described concrete sample (12) and sleeve (7) both sides, and covers with rubber band (14) on the space of both sides.

5. proving installation according to claim 1 is connected on the Anti-leakage instrument after it is characterized in that having an aperture (15) and water inlet pipe (16) linking to each other in the described upward compressed steel backing plate (8) again.

6. one kind with the proving installation of claim 1 method of testing to concrete for hydraulic structure permeance property under load action, it is characterized in that testing procedure is as follows:

(1) pressing machine is tightened and removed to the hydraulic pressure testing machine to spring (5) pressurization, with nuts (6) by steel plate (3) immediately when arriving the authorised pressure value, and this moment, the outside load of pressing was just provided by spring (5);

(2) pressure of spring (5) generation passes through steel plate (4), ball seat (10), goes up compressed steel backing plate (8) transfer function to cylindrical shape concrete sample (12);

(3) Anti-leakage instrument produces press water, press water is injected the inside surface of concrete sample (12) by water inlet pipe (16) and aperture (15);

(4) give space water filling between concrete sample (12) outside surface and the organic glass sleeve (7), the water surface is flushed with spout hole (11), use rubber band (14) to cover sleeve (7) then to avoid the water evaporation;

(5) spout hole (11) of collection on sleeve (7) flows into the infiltration water in the external graduated cylinder;

(6) utilize infiltration water in the graduated cylinder, convert with following derivation formula and try to achieve concrete infiltration coefficient; Circular ring type concrete sample infiltration coefficient computing formula:

$k=\frac{\mathrm{\&mu;q}\&CenterDot;\ln \frac{r_1}{r_2}}{2\mathrm{\&pi;}\&CenterDot;h\&CenterDot;\mathrm{\&Delta;h}}$

In the formula: k-infiltration coefficient (cm/s); Discharge (the cm that collects in the q-unit interval³/ s); r₂The external radius of-annular test-piece (cm); r₁The inside radius of-annular test-piece (cm); The height of h-annular test-piece (cm); Δ h-water flows into the head difference between face and effluent face, the viscosity of μ-water.

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