CN-122016515-A - Cemented sand gravel in-situ testing device and deformation modulus and shear strength testing method

CN122016515ACN 122016515 ACN122016515 ACN 122016515ACN-122016515-A

Abstract

The invention provides a cemented sand gravel in-situ test device and a deformation modulus and shear strength test method, wherein the cemented sand gravel in-situ test device comprises a force transmission seat plate, a plurality of pull rods are hinged to the force transmission seat plate, the pull rods are uniformly distributed around the force transmission seat plate, and the lower ends of the pull rods are hinged to anchor assemblies which are anchored on the ground; the lower side of the force transmission seat plate is sequentially and downwards provided with a force transmission column, a vertical jack, a first base plate and a bearing plate for pressurizing the top of a test piece, wherein a plurality of vertical displacement sensors are distributed on the top of the bearing plate, and the vertical jack is connected with a vertical pressure sensor for measuring the pressure of the vertical jack. The invention realizes the in-situ test of the cemented sand and gravel, has the advantages of low cost, avoiding material disturbance and stress release in the sampling and sample preparation process, realizing true results and accurate data, and providing reliable technical support for mechanical property evaluation of the cemented sand and gravel with large particle size.

Inventors

DONG MIN
YANG HUICHEN
ZHU SHENGMIN
LI DONGFEI
ZHOU HONG
HE RENQIANG
CHEN CAI
NA YINTAI
CHANG XINHUA
ZHENG LIFENG
LI AILI
ZHAO CHUN
Li Qianti
NIU SHUYU
Chen wendeng
XU SHUMEI
BAI LIN
CHEN JUNE
WANG LIN
DING LIANYING
LI JIANDONG
JIA JINSHENG
ZHENG CUIYING
HE JINGFENG
XU YONG

Assignees

新疆葛洲坝大石峡水利枢纽开发有限公司
中国水利水电科学研究院
中能建葛洲坝工程科技有限公司
新疆维吾尔自治区塔里木河流域大石峡水利枢纽工程建设管理中心
温岭市南光地质仪器有限公司
浙江水利水电学院

Dates

Publication Date: 20260512
Application Date: 20260116

Claims (10)

1. The cementing sand gravel in-situ testing device is characterized by comprising a force transmission seat board (1), wherein a plurality of pull rods (2) are hinged to the force transmission seat board (1), the pull rods (2) are evenly distributed around the force transmission seat board (1), the lower ends of the pull rods (2) are hinged to anchoring components, the anchoring components are anchored on the ground, a force transmission column (3), a vertical jack (4), a first base plate (5) and a pressure bearing plate (6) for pressurizing the top of a test piece are sequentially arranged on the lower side of the force transmission seat board (1) downwards, a plurality of vertical displacement sensors (7) are distributed on the top of the pressure bearing plate (6), and a vertical pressure sensor (8) for measuring self pressure is connected to the vertical jack (4).
2. The device for in-situ testing of cemented sand and gravel according to claim 1, wherein the anchoring assembly comprises an anchoring seat (9), an anchor rod (10) is fixed on the anchoring seat (9), the lower end of the anchor rod (10) is anchored into the ground, and the lower end of the pull rod (2) is hinged with the anchoring seat (9).
3. The cemented sand gravel in-situ testing device according to claim 1 is characterized in that a first spherical hinge plate (11) is further arranged on the lower side of the force transmission seat plate (1), the first spherical hinge plate (11) is in spherical contact with the force transmission seat plate (1), and the first spherical hinge plate (11) is fixedly connected with the upper end of the force transmission column (3).
4. The device for in-situ testing of cemented sand and gravel according to claim 3, wherein a cushion block (12) is further arranged between the force transmission column (3) and the vertical jack (4), a boss is arranged at the upper end of the cushion block (12) and extends into the lower end of the force transmission column (3), a groove is arranged at the lower end of the cushion block (12), and the upper end of the vertical jack (4) extends into the groove.
5. The in-situ test device for cemented sand gravel according to any one of claims 1 to 4, further comprising a horizontal jack (13), wherein the horizontal jack (13) is positioned on one side of the test piece, a second base plate (14) is arranged between the first end of the horizontal jack (13) and soil body, a side force transmission plate (15) for pressurizing the side surface of the test piece is arranged between the second end of the horizontal jack (13) and the test piece, a plurality of horizontal displacement sensors (17) are distributed on one side of the test piece away from the side force transmission plate (15), and a horizontal pressure sensor (18) for measuring the self pressure is connected to the horizontal jack (13).
6. The device for in-situ testing of cemented sand and gravel according to claim 5, wherein a second spherical hinge plate (16) is further arranged between the second end of the horizontal jack (13) and the side force transfer plate (15), the second spherical hinge plate (16) is in spherical contact with the side force transfer plate (15), and the second spherical hinge plate (16) is fixedly connected with the second end of the horizontal jack (13).
7. The in-situ test device for cemented sand and gravel according to claim 5, wherein a roller row (19) is further arranged between the first backing plate (5) and the bearing plate (6).
8. The device for in-situ testing of cemented sand and gravel according to claim 5, further comprising an instrument frame (20), wherein the instrument frame (20) is a portal frame, two ends of the instrument frame (20) extend out of the anchoring assembly and are fixed on the ground, the bearing plate (6) is located right below the instrument frame (20), and the reference end of the vertical displacement sensor (7) and the reference end of the horizontal displacement sensor (17) are both fixed on the instrument frame (20).
9. The method for testing the in-situ deformation modulus of the cemented sand gravel is characterized by comprising the following steps of: 1. The test point preparation and field leveling, namely selecting a flat, compact and representative cemented sand and gravel test area on an engineering site, removing all loose particles and floating dust on the surface of the test point, and exposing an undisturbed cemented sand and gravel layer; 2. The device is in place, namely, a bearing plate (6) is precisely placed in the center of a flattened testing surface, the coverage area of the bearing plate (6) is a test piece, and the integral installation of the cemented sand gravel in-situ testing device is completed; 3. Applying a pre-compression load through a vertical jack (4), and then unloading to an initial load; 4. The method comprises the steps of grading loading and data acquisition, wherein a vertical jack (4) carries out grading loading, each time a level of load Pi is applied, initial reading of a vertical displacement sensor under the level of load is recorded, and a sedimentation value Si is recorded every predetermined time; 5. Step unloading and rebound observation, namely after loading to the estimated maximum pressure Pmax and stabilizing, starting step unloading; 6. Data processing and deformation modulus calculation, namely finishing data, drawing a complete P-S curve of load-settlement value, selecting an initial linear section of the P-S curve, and calculating the deformation modulus E 0 of the cemented sand and gravel according to an elastic theoretical formula.
10. The method for testing the in-situ shear strength of the cemented sand gravel is characterized by comprising the following steps of: 1. The test point preparation and field leveling comprises the steps of selecting a flat, compact and representative cemented sand and gravel test area on an engineering site, removing all loose particles and floating dust on the surface of the test point, exposing undisturbed cemented sand and gravel layer, cutting and trimming a regular cuboid test piece, and trimming the top surface, the side surface bearing horizontal thrust and the bottom surface of the test piece; 2. The device is in place, namely the integral installation of the cementing sand gravel in-situ testing device is completed, and a roller row (19) is paved at the bottom of the trimmed test piece; 3. Slowly increasing the vertical pressure step by step to a preset test value, clearing the readings of all the horizontal displacement sensors (17) and the horizontal pressure sensors (18), and preparing for starting a shear test; 4. the horizontal thrust is applied and the data are synchronously collected, namely a horizontal jack (13) is started, the horizontal thrust is applied to a test piece at a constant displacement rate, and meanwhile, the following data are collected: time t, vertical stress sigma, horizontal shear stress tau, shear displacement δh, vertical displacement δv; 5. and (3) recording the test termination and the test piece damage state, namely judging that the test piece is sheared and damaged when one of the following conditions occurs, terminating the test, and recording the final damage form of the test piece: 1) The horizontal shear stress tau steadily decreases after the peak value appears; 2) The shear displacement delta h is continuously increased, and the change rate of the horizontal shear stress tau is obviously gentle; 3) The shearing displacement amount reaches 1/15 to 1/10 of the side length of the test piece; 6. And (3) carrying out data processing and parameter calculation, namely drawing a horizontal shear stress tau-shear displacement delta h relation curve, and determining the shear strength of the test piece under the vertical stress sigma from the curve.

Description

Cemented sand gravel in-situ testing device and deformation modulus and shear strength testing method Technical Field The invention relates to the technical field of a device for testing mechanical properties of a dam material, in particular to a device for testing cemented sand gravel in situ and a method for testing deformation modulus and shear strength. Background The cemented sand gravel is a novel dam building material in the field of hydraulic engineering. The cement is prepared by mixing a small amount of cementing materials such as cement, fly ash and the like with natural gravel materials which are not screened and washed on an engineering site, simply mixing, paving, vibrating and rolling (or pouring and vibrating), and finally forming a cementing body with specific compressive strength, shear strength and deformation resistance. At present, the material is successfully applied to forty reservoir dam, cofferdam and embankment projects in China, and the accurate test of the in-situ mechanical property of the material becomes a key link for guaranteeing the safety and quality of projects. However, the unique weak cementing properties and broad size grading distribution of cemented sand gravel as a new material with structural and material properties intermediate between concrete and earth materials makes traditional in situ testing methods a significant challenge. If the horizontal shearing method based on the rigid shearing box is used in the field of soil and stones, the primary cementing structure and the aggregate interlocking effect of the horizontal shearing method can be seriously disturbed due to the forced preset shearing surface, so that the test result is seriously deviated from the real strength. If the method is directly applied to a prefabricated surface test piece direct shear method in the concrete field, the cemented sand gravel has the characteristics of large aggregate particle size (often more than 150 mm), wide grading range, large discreteness and the like, and the conventional size test piece is difficult to contain the representative grading, so that the problems of large data discreteness, prominent size effect, incapability of reflecting aggregate shearing and cementing surface composite damage mechanism and the like exist. The two traditional in-situ test methods respectively aiming at the soil and stone granular bodies and the concrete strong cementing body have intrinsic limitations due to mismatch with transitional mechanical behaviors of the cemented sand and gravel. In summary, no device and related standard method specially used for testing the shear strength and the deformation modulus of the in-situ bonded sand gravel exist in the industry at present, and the device and the method become key technical bottlenecks for restricting the safety evaluation and the engineering popularization of the material. Therefore, there is a great need to develop a specific test theory and method that can consider both the structural integrity and the material heterogeneity, and to provide a device and method that is suitable for on-site conditions and can obtain in-situ real mechanical parameters, which has become an urgent need to promote safe and reliable application of the material. Disclosure of Invention In order to solve at least one of the technical problems, the invention provides a cemented sand gravel in-situ testing device and a deformation modulus and shear strength testing method. The technical scheme for solving the technical problems is as follows: The invention provides an in-situ testing device for cemented sand gravel, which comprises a force transmission seat plate, wherein a plurality of pull rods are hinged to the force transmission seat plate, the pull rods are uniformly distributed around the force transmission seat plate, an anchoring assembly is hinged to the lower end of each pull rod, the anchoring assembly is anchored on the ground, a force transmission column, a vertical jack, a first backing plate and a pressure bearing plate for pressurizing the top of a test piece are sequentially arranged on the lower side of the force transmission seat plate downwards, a plurality of vertical displacement sensors are distributed on the top of the pressure bearing plate, and the vertical jack is connected with a vertical pressure sensor for measuring the self pressure. The beneficial effects of the invention are as follows: According to the invention, the in-situ test of the cemented sand gravel is realized, repeated carrying, erection and calibration processes of equipment can be avoided, the total time of single-point test is shortened by more than 50%, the test is efficient, and the cost is economical. Meanwhile, the device can be used for testing the deformation modulus and shearing strength, so that two sets of traditional special equipment can be replaced, the equipment purchasing, maintenance and manual operation costs are obviously reduced, and the device ha