A rock sample shear box for simulating blasting vibration effect

Abstract

The present invention relates to a rock sample shear box for simulating blasting vibration effect, which is provided with an upper shear box and a lower shear box. A cavity for placing a rock sample is provided at the center of the shear box. The upper shear box and the lower shear box are respectively provided with vibration signal monitoring holes and rectangular windows for placing a filter pad group on the sides in the vertical shear direction; displacement monitoring holes are provided in the middle of both sides of the shear box along the shear direction of the shear box, and a sensor fixing frame is provided on the upper shear body on one side of each displacement monitoring hole. The shear box has a simple structure, scientific design, and convenient loading and unloading. It is suitable for indoor rock sample compression and shearing tests under the action of simulated blasting vibration effect, and can truly and accurately reflect the influence of different blasting vibration response main frequencies and peak velocities on rock samples, and has high test efficiency and reliable test results.

Description

Technical Field

[0001] The invention relates to a shear box, in particular to a rock sample shear box for simulating blasting vibration effect. Background Art

[0002] With the large-scale development of infrastructure construction, blasting operations are often required in the construction process of various projects. The vibration generated by blasting will have a significant impact on the strength of the rock mass itself and the stability of the slope, which may lead to accidents such as landslides and collapses. Therefore, it is of great theoretical and practical significance to study the influence of blasting vibration on the mechanical strength of rock mass. At present, the influence of blasting vibration on the mechanical strength of rock mass is mainly studied through indoor tests. During the compression and shear test, the rock sample is subjected to dynamic impact to simulate the influence of blasting vibration. The indoor test method has the advantages of simple operation and reliable test results. However, the existing test equipment is not easy to accurately simulate and directly monitor the blasting vibration during the compression and shear test.

[0003] Generally, the existing shear boxes have the following main problems: the simulation of the blasting vibration signal is inaccurate, that is, after the dynamic excitation is applied during the test, the vibration response frequency and response speed peak value generated by the rock sample are greatly different from the actual vibration signal parameters; it is not easy to directly monitor the vibration response of the rock sample during the test, but the vibration response signal of the shear box or other components in contact with the rock sample is monitored, and the monitoring results have large errors. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a rock sample shear box that simulates the blasting vibration effect. The use of this shear box can truly and accurately simulate the influence of blasting vibration on rock samples in a compression and shear state, and the test efficiency is high and the test results are reliable.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a rock sample shear box simulating the blasting vibration effect is provided, which is provided with an upper shear box, a lower shear box and a normal loading pad; the upper shear box is formed by connecting an upper top plate and an upper shear body with hexagon socket bolts; the lower shear box is formed by connecting a lower shear body and a lower bottom plate with hexagon socket bolts; a cavity for placing the rock sample is provided at the center of the upper shear box and the lower shear box, the normal loading pad is placed on the rock sample, the bottom of the normal loading pad is in contact with the upper end face of the rock sample, and the top of the normal loading pad is in contact with a dynamic loading structure for applying a normal load;

[0006] The upper shear box has a rectangular window in the middle of one side in the upper shear body perpendicular to the shear direction as a vibration signal monitoring hole; the lower shear box on the other side opposite to the vibration signal monitoring hole has a rectangular window in the middle for placing the filter pad block group;

[0007] A square groove is provided in the middle of both sides of the upper shear box and the lower shear box along the shear direction as a displacement monitoring hole, which is also an observation port for observing the shearing process of the rock sample; a sensor fixing frame is provided on the upper shear body on one side of each displacement monitoring hole;

[0008] The sensor fixing frame is composed of a base, a fixing card and bolts. The base is installed on the side of the upper shear body through the bolts and bolt holes, and the fixing card is also fixed on the base through the bolts.

[0009] The filter pad block group is composed of two or more filter pad blocks. A pin threaded hole is opened at the center of each filter pad block, and the filter pad block group is formed by connecting the threaded pin and the pin threaded hole.

[0010] The filter pad block group is combined by using filter pad blocks of the same material or different materials.

[0011] The sensor fixing frame is used to install the displacement sensor, and the sensor is clamped between the fixing card and the base, and the clamping degree of the sensor is controlled by adjusting the bolt.

[0012] The filter pad can be made of metal materials, such as copper, aluminum, stainless steel, etc., or made of resin materials, such as polyethylene, polyvinyl chloride, etc.

[0013] Compared with the prior art, the rock sample shear box for simulating blasting vibration effect of the present invention has the following beneficial effects:

[0014] ①. The present invention places a rock sample at the center of the upper shear box and the lower shear box, and a normal loading pad is provided on the upper part of the rock sample, the top of which contacts the dynamic loading structure for applying the normal load, and the bottom directly contacts the upper end face of the rock sample, so as to ensure that the normal load is fully applied to the upper end face of the rock sample, avoid the upper shear body from bearing the normal load and increasing the friction between the upper and lower shear boxes, and make the test results more accurate.

[0015] ②. The upper shear body of the upper shear box of the present invention is provided with a vibration signal monitoring hole on one side perpendicular to the shear direction. The vibration signal monitoring hole reserves space for the installation of a sensor for monitoring the vibration signal. The sensor for monitoring the vibration signal can be directly pasted on the rock sample in the vibration signal monitoring hole to accurately measure the vibration response signal of the rock sample under impact load excitation, thereby avoiding measurement errors caused by the sensor contacting other media.

[0016] ③. The lower shear body of the lower shear box of the present invention is perpendicular to the middle of the shear direction, and is provided with a rectangular window for placing a filter pad group on the other side of the vibration signal monitoring hole. Since the filter pad group and the lower shear box are not fixed together, the impact load applied by the dynamic impact device can be directly transmitted to the rock sample through the filter pad group, thereby avoiding the dynamic impact device impacting the entire lower shear body to cause the shear box to vibrate, disturb the normal operation of the displacement sensor, and cause unnecessary energy loss.

[0017] ④. The upper shear body of the upper shear box of the present invention is provided with sensor fixing frames on both sides along the shear direction. The sensor fixing frames are installed on the sides of the upper shear body, which can ensure that the displacement sensor is firmly clamped on the upper shear body. The upper shear body remains stationary relative to the test system during the test, thereby ensuring that the displacement sensor is not affected by the shear load and vibration impact, thereby improving the reliability of the displacement measurement results.

[0018] ⑤. The filter pad block group of the present invention is formed by connecting two or more filter pad blocks, and the filter pad block group is connected by filter pad blocks of the same or different materials. A threaded pin hole is opened in the center of each filter pad, and threaded pins are used to connect each filter pad. During the experiment, the main response frequency of the rock sample under vibration excitation can be changed by changing the number of filter pads and the different material combinations of the filter pads, which is beneficial for the test system to accurately and conveniently simulate the main response frequencies of different rock samples.

[0019] ⑥. The shear box of the present invention has a simple structure, scientific design, and is easy to load and unload. The shear box of the present invention is suitable for indoor rock sample compression and shear tests under simulated blasting vibration effects, and can conveniently simulate the effects of different blasting vibration response main frequencies and peak velocities on rock samples. The test efficiency is high and the results are consistent with the actual situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the I-axis structure of the rock sample shear box for simulating blasting vibration effects of the present invention.

[0021] Figure 2 It is a schematic diagram of the II axonometric structure of the shear box of the present invention.

[0022] Figure 3 For the present invention Figure 2 Schematic diagram of the main cross-sectional structure.

[0023] Figure 4 It is a schematic diagram of the axonometric structure of the shear box filter pad of the present invention.

[0024] Figure 5 It is a schematic diagram of the axonometric structure of the sensor fixing frame of the present invention.

[0025] In the figure: 1—normal loading pad; 2—hexagon socket bolt; 3—upper top plate; 4—upper shear body; 5—filter pad group; 6—threaded pin; 7—lower bottom plate; 8—lower shear body; 9—sensor fixing bracket; 10—displacement monitoring hole; 11—vibration signal monitoring hole; 12—rock sample; 51—filter pad A; 52—filter pad B; 61—threaded pin hole; 91—bolt; 92—fixing card; 93—base; 94—bolt hole. DETAILED DESCRIPTION

[0026] The rock sample shear box for simulating blasting vibration effect of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0027] Embodiment 1: The present invention provides a rock sample shear box for simulating blasting vibration effect, the structure of the shear box is as follows: Figures 1 to 5 The shear box comprises an upper shear box, a lower shear box, a normal loading pad 1, a sensor fixing frame 9 and a filter pad group 5; a cavity for placing a rock sample 12 is provided at the center of the upper shear box and the lower shear box, a normal loading pad 1 is provided on the upper part of the rock sample, the top of the normal loading pad 1 is in contact with a dynamic loading structure for applying a normal load, and the bottom of the normal loading pad is in direct contact with the upper end surface of the rock sample.

[0028] See also Figure 1 , 3 The upper shear box is provided with an upper top plate 3 and an upper shear body 4 connected by hexagon socket bolts 2; the lower shear box is provided with a lower bottom plate 7 and a lower shear body 8 also connected by hexagon socket bolts;

[0029] See also Figure 1 , 2 The upper shear box has an upper shear body 4 perpendicular to the shearing direction, and a rectangular window is provided in the middle of one side as a vibration signal monitoring hole 11; a rectangular window for placing a filter pad block group 5 is provided in the middle of the lower shear body 8 of the lower shear box on the other side opposite to the vibration signal monitoring hole;

[0030] The filter pad group 5 is formed by connecting two filter pads, filter pad A 51 and filter pad B 52. The center of the two filter pads is provided with a threaded pin hole 61, and the filter pad group 5 is connected by the threaded pin 6 and the threaded pin hole 61. In this embodiment, the filter pads are made of two identical copper filter pads.

[0031] See also Figure 1 , 5A square groove is provided in the middle of both sides of the upper shear box and the lower shear box along the shear direction as a displacement monitoring hole 10, which is also an observation port for observing the shearing process of the rock sample. A sensor fixing frame 9 is provided on the upper shear body 4 on one side of each displacement monitoring hole. The sensor fixing frame is composed of a base 93, a fixing card 92 and a bolt 91. The base is installed on the side of the upper shear body by inserting the bolt into the bolt hole 94, and the fixing card is also installed on the base through the bolt and the bolt hole; the sensor fixing frame is used to fix the displacement sensor, the displacement sensor is clamped between the fixing card and the base, and the clamping degree of the displacement sensor is controlled by adjusting the bolt.

[0032] When the shear box of the present invention is used to simulate the blasting vibration effect test indoors, the test should be carried out together with the supporting test system, which includes a displacement sensor, a sensor for monitoring vibration, a blasting vibrometer, a tangential actuator, a normal actuator, a dynamic impact device and a test station; it is also necessary to prepare a rectangular rock sample 12 with the same size as the inner cavity of the shear box. The rock sample prepared in this embodiment is a rectangular rock sample of 150mm×75mm×75mm. After the surface is polished and smooth, it is placed in the cavity of the lower shear box, and then the cavity of the upper shear box is aligned with the rock sample and installed, and the normal loading pad 1 is installed on the upper part of the rock sample; then the corresponding sensors are installed in the displacement monitoring hole 10 and the vibration signal monitoring hole 11 respectively. The test process is as follows:

[0033] ⑴. Select the blasting vibration signal to be simulated for analysis to determine the main frequency and peak vibration velocity of the vibration response that the rock sample needs to generate under the impact load, and at the same time determine the excitation frequency and the size of the compression and shear load used to simulate the vibration, and formulate a test plan;

[0034] ⑵, place the filter pad group 5 in the rectangular window on one side of the shear box where the rock sample 12 is installed; Figure 4 As shown. Install the displacement sensor on the sensor fixing frame 9, and at the same time, directly stick the vibration monitoring sensor on the rock sample at the vibration signal monitoring hole 11, and connect the other end of the vibration monitoring sensor to the blasting vibrometer; push the shear box to the test station in the test system, and check whether the instruments, devices and sensors in the test system can work normally;

[0035] (3) Start the tangential actuator and the normal actuator to apply a predetermined compressive shear load to the rock sample through the shear box. During the compressive shear process, a dynamic impact device is used to perform dynamic intermittent impact on the filter pad group 5 according to the test plan;

[0036] (4) Simulate the on-site blasting vibration effect by impacting the rock sample with the filter pad group, observe and analyze whether the vibration signal monitored by the blasting vibration meter is similar to the main frequency of the blasting vibration signal to be simulated; if not, adjust the material and combination of the filter pad group according to the vibration signal value feedback, that is, adjust one of the filter pads in the filter pad group or replace all the filter pads with filter pads of other materials, or adjust the number of filter pads, impact the filter pad group again after adjustment, observe again, and repeat this step until the observed vibration signal is similar to the main frequency of the simulated blasting vibration signal. Since the signal value feedback can be used, it can be observed that the vibration signal is similar to the main frequency of the simulated blasting vibration signal after several adjustments, and record the determined filter pad group material and combination;

[0037] (5) Adjust the impact energy of the dynamic impact device, observe whether the peak vibration velocity of the rock sample monitored by the blasting vibration meter is similar to the peak vibration velocity of the blasting vibration signal to be simulated, and repeat this step if not similar, and adjust the impact energy value according to the feedback of the vibration signal until the peak vibration velocity of the rock sample is similar to the peak vibration velocity of the blasting vibration signal to be simulated, and record the determined impact energy value;

[0038] (6) Replace the rock sample 12, and perform a compression and shear test simulating the blasting vibration according to the excitation frequency and compression and shear load determined in the test plan, the material and combination of the filter pad group determined in step (4), and the impact energy determined in step (5), and observe and record the test data measured by the displacement sensor and the vibration monitoring sensor until the test is completed;

[0039] ⑺. After the test is completed, push the shear box away from the test station, open the shear box and take out the rock sample, clean the internal cavity of the shear box and install the shear box for next use.

[0040] Embodiment 2: The present invention provides a rock sample shear box for simulating blasting vibration effects, and its structure and test process are basically the same as those of Embodiment 1; the only difference is that the filter pad group uses filter pads made of polyethylene and polyvinyl chloride respectively.

[0041] The shear box of the present invention is suitable for indoor experiments to simulate the influence of blasting vibration on the mechanical properties of rock samples. It can conveniently simulate the influence of different blasting vibration response frequencies and peak velocities on rock samples. The test efficiency is high and the results are consistent with the actual situation.

Claims

1. A rock sample shear box for simulating blasting vibration effect, comprising an upper shear box, a lower shear box and a normal loading pad; the upper shear box is formed by connecting an upper top plate and an upper shear body with hexagon socket bolts; the lower shear box is formed by connecting a lower shear body and a lower bottom plate with hexagon socket bolts; a cavity for placing the rock sample is provided at the center of the upper shear box and the lower shear box, the normal loading pad is placed on the rock sample, the bottom of the normal loading pad contacts the upper end face of the rock sample, and the top of the normal loading pad contacts the dynamic loading structure for applying the normal load; characterized in that: The upper shear box has a rectangular window in the middle of one side in the upper shear body perpendicular to the shear direction as a vibration signal monitoring hole; a rectangular window for placing a filter pad block group is provided in the middle of the lower shear body of the lower shear box on the other side opposite to the vibration signal monitoring hole; a dynamic impact device is used to perform dynamic intermittent impact on the filter pad block group, and the filter pad block group is used to impact the rock sample to simulate the on-site blasting vibration effect; A square groove is provided in the middle of both sides of the upper shear box and the lower shear box along the shear direction as a displacement monitoring hole, which is also an observation port for observing the shearing process of the rock sample; a sensor fixing frame is provided on the upper shear body on one side of each displacement monitoring hole; The sensor fixing frame is composed of a base, a fixing card and bolts. The base is installed on the side of the upper shear body through the bolts and bolt holes, and the fixing card is also fixed on the base through the bolts.

2. The rock sample shearing box for simulating blasting vibration effect according to claim 1 is characterized in that: The filter pad block group is composed of two or more filter pad blocks. A pin threaded hole is opened at the center of each filter pad block, and the filter pad block group is formed by connecting the threaded pin and the pin threaded hole.

3. The rock sample shear box for simulating blasting vibration effect according to claim 1, characterized in that: The filter pad block group is combined by using filter pad blocks of the same material or different materials.

4. The rock sample shear box for simulating blasting vibration effect according to claim 1, characterized in that: The sensor fixing frame is used to install the displacement sensor, and the sensor is clamped between the fixing card and the base, and the clamping degree of the sensor is controlled by adjusting the bolt.

Images