CN101178395A - Non-contact rock-soil three-way shrinkage test device and test method - Google Patents

Abstract

The invention relates to a non-contact rock soil three-dimensional contraction testing device and a testing method, the invention is composed of a square frame, a laser displacement sensor, a laser displacement sensor support, soil sample and a soil sample support, a guide slot which is used for translating the laser displacement sensor support is arranged on the square frame, a wedge-shaped fixed slot which is used for fixing the soil sample support is arranged on a bottom board, and the position of the laser displacement sensor on the laser displacement sensor support can be regulated by inner thread, an adjusting screw rod, a manual rotating wheel and a screw rod which is provided with a hole. Therefore, the invention can carry out the measurement of the three-dimensional expansion and contraction deformation of the soil sample in the test, so as to realize the accurate measurement of the three-dimensional expansion and contraction deformation performance of the soil sample.

Description

Non-contact rock-soil three-way shrinkage test device and test method

                      

The invention relates to a test device for indoor measurement of three-dimensional shrinkage deformation of fine-grained soil in soil mechanics and foundation engineering.

Background technique

At present, the instruments and equipment for measuring the shrinkage index of fine-grained soil at home and abroad are generally composed of brackets, contact displacement measuring devices (such as mechanical gauges or displacement sensors), measuring plates, perforated plates, pads, soil samples, etc. When performing shrinkage test, the prepared soil sample is generally placed on a perforated plate with a ring knife, and the mass of the sample and the perforated plate is weighed. Then install the contact vertical displacement measuring device on the bracket, and record the initial reading of the vertical displacement. The shrinkage test is carried out at a temperature of 1-30°C. According to the moisture content and shrinkage speed of the sample, measure the vertical deformation and quality of the sample every 1-4 hours, such as after the shrinkage deformation of the sample is slowed down. , the measurement time interval can be further increased until the vertical deformation value of the sample tested at two longer time intervals is basically unchanged. After the vertical deformation measurement of the sample is completed, the sample is dried and its volume is measured. Calculate the linear shrinkage, volume shrinkage and shrinkage coefficient of the sample according to the standards or regulations.

When the current shrinkage test device is used for the shrinkage test, for the compacted soil sample, because the soil sample is relatively uniform, the deformation of the sample during the dehydration shrinkage process is also relatively uniform, and generally there will be no large local deformation unevenness, displacement The vertical deformation value measured by the measuring equipment can basically represent the vertical deformation of the whole sample. However, for undisturbed soil samples, due to the inhomogeneity of natural soil samples and the influence of factors such as the structure and cracks of soil samples, local deformation of soil samples will be more or less uneven during the process of dehydration shrinkage, especially in water-containing soil samples. When the rate is reduced to close to the shrinkage limit, for cracked clay, local warping or even block loss often occurs. The phenomenon of abnormal "expansion" or "shrinkage" will appear in the measured deformation value, which will bring great difficulties to the processing of test data and the accurate calculation of sample shrinkage index, and even cause distortion of test results, and affect the shrinkage performance of soil samples. Cases of misjudgment.

In addition, the current contact shrinkage test device can only measure the vertical shrinkage deformation of the soil sample, but cannot simultaneously measure the horizontal deformation of the soil sample. No matter the compacted soil sample or the undisturbed soil sample has a certain degree of anisotropy, there is a certain difference in the anisotropic shrinkage deformation during the shrinkage process, that is, the anisotropic shrinkage index of the soil sample is different. The current contact shrinkage test device cannot use the same soil sample to measure its vertical and horizontal deformation at the same time, which brings great difficulties to the study of the shrinkage deformation characteristics of soil anisotropy.

Contents of the invention

The purpose of the invention is: on the one hand, to solve the problem that the current cohesive soil shrinkage test device cannot measure the accurate shrinkage deformation of the undisturbed soil sample under the condition of low water content well in the test process; It is difficult to measure the vertical and horizontal deformation of soil simultaneously with the same soil sample. The invention provides a non-contact rock-soil three-way shrinkage test device, which can conveniently and accurately measure the overall vertical deformation value of the soil sample at each shrinkage stage during the test process according to the characteristics of the sample, which is the index of the shrinkage index of the soil sample. Accurate determination provides a guarantee, and can simultaneously measure the vertical and horizontal shrinkage deformation indicators of the soil, which provides help for the study of the anisotropic deformation characteristics of the soil.

In order to achieve the above object, the non-contact rock-soil three-way shrinkage test device of the present invention is made up of square frame, laser displacement sensor, laser displacement sensor support, soil sample and soil sample support; It is characterized in that the square frame consists of a frame top frame 12 , a frame side frame 13, and a frame base 14; the frame base 14 is provided with a wedge-shaped fixing groove 22 and a positioning baffle 23 for fixing the wedge-shaped bottom plate 20 of the soil sample support. The soil sample support is composed of a soil sample support support plate 19, a perforated plate 18 with a circular hole 21, and a wedge-shaped bottom plate 20 of the soil sample support; A laser displacement sensor bracket guide groove 17 is provided; the laser displacement sensor bracket consists of a laser displacement sensor 1, a screw rod with a hole 2, an external fixing bolt 3, an internal fixing bolt 4, a laser displacement sensor fixing seat 5 with an internal thread 11, and a laser displacement sensor Cable line 6, laser displacement sensor screw mandrel holder 7, laser displacement sensor adjustment screw mandrel 8, bearing 9, manual runner 10, laser displacement sensor holder guide rod 15, laser displacement sensor support guide rod 16 form. The holed screw 2 is used to fix the laser displacement sensor 1, and adjust the distance between the laser displacement sensor 1 and the soil sample 24 through the outer fixing bolt 3 and the inner fixing bolt 4; because the laser displacement sensor fixing seat 5 has an internal thread 11 , the laser displacement sensor adjustment screw rod 8 is rotated by the manual runner 10, and the laser displacement sensor 1 can be driven to move freely along the direction of the laser displacement sensor holder guide rod 15; the laser displacement sensor bracket can also pass through the laser displacement sensor bracket guide rod 16 Translate in the guide groove 17 of the laser displacement sensor bracket.

First process a square rigid frame with a guide groove and a detachable laser displacement sensor bracket. The size of the rigid frame is determined according to the size of the laser displacement sensor 1 and the soil sample 24. The range of the laser displacement sensor 1 depends on the soil. The initial state, expansion and contraction of the sample 24, and the accuracy of the laser displacement sensor 1 depend on the purpose and requirements of the test. When carrying out the shrinkage test, the soil sample 24 is first processed and prepared according to the requirements of the test, carefully placed on the perforated plate 18 of the soil sample support of the soil sample 24, and the initial weight is weighed, and then the soil sample 24 and the soil sample The sample support is put into the square frame base together, and the wedge-shaped bottom plate 20 of the soil sample support is pushed into the wedge-shaped fixing groove 22, and the wedge-shaped bottom plate 20 of the soil sample support is in good contact with the positioning baffle plate 23. Adjust the positions of the five laser displacement sensors 1, and measure a certain number of initial values of the laser displacement sensors 1 on the five surfaces of the soil sample 24 according to the requirements of the test. Then, according to the dehydration shrinkage of the soil sample 24, the steps of weighing and reading the readings of the displacement sensor 1 can be repeated until the shrinkage of the soil sample 24 is stable.

Due to the use of the laser displacement sensor 1, non-contact measurement can be realized, and the laser displacement sensor 1 can be positioned and measured at any point in the two directions of the soil sample 24 plane, and can be measured according to the grid points drawn in advance , and can also be measured at any point according to the actual deformation of the soil sample 24, so that the measurement of the expansion and contraction deformation of the soil sample 24 is more representative and more accurate.

The soil sample 24 can also be processed into the same shape as the conventional shrinkage test by using a ring cutter according to the purpose and requirements of the test, and the vertical and horizontal shrinkage deformation can be measured.

Another advantage of the device is that it can measure the three-dimensional expansion of the soil sample 24 slowly absorbing water under no-load conditions, and the interference to the measurement of the expansion deformation of the soil sample 24 is reduced to the minimum.

Description of drawings

Figure 1 is a diagram of the non-contact three-way shrinkage test device for rock and soil.

Fig. 2 is an A-A sectional view of the non-contact rock-soil three-way shrinkage test device.

Figure 3 is a front view of the laser displacement sensor bracket.

Fig. 4 is a B-B sectional view of the laser displacement sensor bracket.

Fig. 5 is a C-C sectional view of the laser displacement sensor bracket.

Fig. 6 is a D-D sectional view of the laser displacement sensor bracket.

Fig. 7 is an E-E sectional view of the laser displacement sensor bracket.

Fig. 8 is an F-F sectional view of the laser displacement sensor bracket.

Fig. 9 is a front view of the soil sample support and its G-G section view.

Fig. 10 is a top view of the soil sample support and its H-H section view.

As shown in the figure: laser displacement sensor 1, screw with hole 2, external fixing bolt 3, internal fixing bolt 4, laser displacement sensor fixing seat 5, laser displacement sensor cable 6, laser displacement sensor screw fixing seat 7, laser displacement sensor Sensor adjustment screw 8, bearing 9, manual wheel 10, internal thread 11, frame top frame 12, frame side frame 13, frame base 14, laser displacement sensor fixing seat guide rod 15, laser displacement sensor bracket guide rod 16, laser Displacement sensor bracket guide groove 17, perforated plate 18, soil sample support support plate 19, soil sample support wedge-shaped bottom plate 20, circular hole 21, wedge-shaped fixing groove 22, positioning baffle plate 23, soil sample 24.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Fig. 1 is the non-contact rock-soil three-way shrinkage test device that adopts cubic soil sample of the present invention, before carrying out test, earlier carries out suitable processing to used soil sample 24, and soil sample 24 is cut into regular regular hexahedron, In order to measure the three-dimensional shrinkage deformation of the soil sample 24 according to as few measurement points as possible during the shrinkage test.

When carrying out the test, the square frame made up of the frame top frame 12, the frame side frame 13, and the frame base 14 and the laser displacement sensor 1, the screw with holes 2, the external fixing bolts 3, the internal fixing bolts 4, and the inner thread 11 Laser displacement sensor holder 5, laser displacement sensor cable 6, laser displacement sensor screw holder 7, laser displacement sensor adjustment screw 8, bearing 9, manual wheel 10, laser displacement sensor holder guide rod 15, laser displacement The movable support that sensor support guide bar 16 forms is assembled, and the soil sample bearing group that will place soil sample 24 is ready. Then the prepared soil sample 24 is placed on the perforated plate 18 with a circular hole 21 in the soil sample holder, and the soil sample 24 and the soil sample holder are placed on a weighing balance to weigh the initial weight. Then move the laser displacement sensor bracket on the front of the non-contact rock-soil three-way shrinkage test device along the direction of the laser displacement sensor bracket guide groove 17, so that the wedge-shaped bottom plate 20 of the soil sample support can be easily inserted into the wedge-shaped fixing groove on the frame base 14 22, then the soil sample support is pushed into contact with the positioning baffle plate 23 in place, and fixed. The laser displacement sensor 1 that is fixed on the laser displacement sensor holder 5 of the front, back, left, right and top one by one passes through the laser displacement sensor holder guide rod 15, the laser displacement sensor bracket guide rod 16, the laser displacement sensor bracket guide Groove 17, manual wheel 10 and laser displacement sensor adjustment screw 8 are adjusted to the position corresponding to soil sample 24, and read the initial reading of laser displacement sensor 1 of front, back, left, right and top in sequence, each laser displacement The number of reading data of the sensor 1 on one surface of the soil sample 24 can be executed according to the plan determined before the test, or can be flexibly controlled according to the shrinkage and deformation of the soil sample 24 at different stages.

The non-contact rock-soil three-way shrinkage test device of the present invention can measure the three-way expansion and contraction deformation of the soil sample 24 in real time according to the needs of the test, and conveniently perform non-contact deformation measurement, so that the three-way expansion and contraction of the soil sample 24 The shrinkage deformation test is more convenient and accurate. Moreover, the structure is simple and the operation is convenient.

Claims (5)

1. A non-contact rock-soil three-way shrinkage test device and test method are composed of a square frame, a laser displacement sensor and a secondary instrument, a laser displacement sensor support, a soil sample and a soil sample support; it is characterized in that the square frame consists of The frame top frame (12), the frame side frame (13), and the frame base (14); the frame top frame (12), the frame side frame (13) and the frame base (14) are provided with a laser displacement sensor bracket guide groove ( 17); the frame base (14) is provided with a wedge-shaped fixing groove (22) and a positioning baffle (23); the laser displacement sensor bracket is composed of a screw with a hole (2), an outer fixing bolt (3) and an inner fixing bolt (4 ), laser displacement sensor holder (5), internal thread (11), manual wheel (10), laser displacement sensor adjustment screw (8), laser displacement sensor holder guide rod (15), laser displacement sensor bracket guide Rod (16) forms. 2. The non-contact rock-soil three-way shrinkage test device and test method according to claim 1 is characterized in that the holed screw rod (2) on the laser displacement sensor support is used to fix the laser displacement sensor (1), and passes The outer fixing bolt (3) and the inner fixing bolt (4) adjust the distance between the laser displacement sensor (1) and the soil sample (24); 8), the holed screw (2) is used to adjust the position of the laser displacement sensor (1) on the laser displacement sensor bracket. 3. The non-contact rock-soil three-way shrinkage test device and test method according to claim 1, is characterized in that the swelling on the front, back, left, right, and upper 5 faces of the soil sample (24) can be measured simultaneously. Shrinkage deformation, measuring point position of soil sample (24) expansion and contraction deformation can be fixed in advance, also can be adjusted at any time according to soil sample (24) expansion and contraction deformation situation, the quantity of measuring point also can be according to soil sample (24) It depends on the situation of expansion and contraction deformation and the test. 4. non-contact rock-soil three-way shrinkage test device and test method according to claim 1, the size of square frame, laser displacement sensor support and soil sample support can be according to the size and expansion and contraction of soil sample (24) The size and the size of the laser displacement sensor (1) are processed into different specifications. 5. The non-contact rock-soil three-way shrinkage test device and test method according to claim 1 is characterized in that the laser displacement sensor (1) can be used according to the expansion and contraction performance of the soil sample (24) and the requirements for test accuracy Different laser displacement sensors (1) with different measuring ranges and precisions are replaced.

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