Combined ultrathin flexible uniformly distributed pressure loading device for geomechanical model tests

Technical Field

The invention relates to a loading device, in particular to a mechanical model test to composite ultra-thin flexible uniform distributed pressure loading device.

Background Art

The geological mechanical model test in complex test process to highlight major contradictions, is convenient to grasp and, internal links of the phenomenon found. In foreign countries, to Furman greenhaven LED experts in Italy a model test structure of the project geological mechanical model experimental technology. Subsequently, the United States, Germany, France, England and Japan and other countries have also conducted a large number of model testing and research. In domestic, the Tsinghua University, the GSD scv scientific research three, many research institutes Shandong University, domestic to the many large-scale projects the geological mechanical model experimental study.

Loading the model boundary geological mechanical model test is one of the key technologies in, because it has a direct relationship to the model boundary loading effect and accuracy, the model test loading ground stress whether real analog engineering practical stress state plays an important role, will have a direct impact on model body formed in the field of stress (strain) and the degree of uniformity of the authenticity of the experiment results. In order to ensure the accuracy of the test results, the original real simulation test loading condition of the ground is particularly important, therefore, that produce a uniform stress field in the model, as far as possible should be reduced is not uniform on the surface of the model and the range of the depth of field test results of the model is very important.

At loading from the existing models, the application of the load on the surface of the model there are three main ways:

(1) the hydraulic cylinder through the rigid thruster loading, rigid thruster can be a triangular distribution block or trapezoidal distribution block. The method comprises loading the load is large, large stroke, is easy to control, and the like, but the loading pressure uniformity deviation is large, resulting in a very poor model should be variable field uniformity, it is difficult to reflect the engineering stress state. The special as the middle of the excavation of the cavern, leading to an inevitable non-uniform deformation of the model boundary, the method of loading the boundary load to the non-uniformity is more obvious, that is also not conducive to loading pressure head at the same time with the boundary of the transverse deformation of the synchronization, therefore, the model boundary low loading accuracy.

(2) using traditional hydraulic loading of the rubber, can realize the flexible uniform loading on the surface of the model, in particular when the model produced on the surface of the non-uniform deformation of the can still be evenly loaded. However, because the loading load low intensity, stroke is small, is not able to meet the model larger deformation and the requirement of high strength, can not reach the deep mining test the high stress loading requirements; moreover, its troublesome production, short service life, generally only can meet the need for a trial.

(3) the above two methods is not high precision requirements in the test of the condition of some engineering problems can be solved. With the gradual expansion of the-scale projects, continuously improve precision, these two kinds of loading methods have become increasingly exposed defects of the same. In order to solve the above-mentioned problem, the GSD scv scientific research three design of the piston type are distributed pressure loader (ZL   02213775.0), can be uniformly distributed load on a model, but also solves the problem that the model test problem of flexible force-transferring uniform loading. However, piston type are distributed pressure loader more complex structure, high processing requirements on manufacturing accuracy, the price is relatively high.

A comprehensive analysis of the above-mentioned units in the model test loading system, mainly of the following deficiencies:

1. in fact, most of the loading system is a hydraulic cylinder + the rigid loading system, load deviation is large, is easy to cause stress concentration, the surface of the model not be able to achieve the purpose of uniformly distributed load.

2. hydraulic bag loading due to the stroke is small, movable, bad durability, can only be unidirectional loading, the perforation on the wiring and the like, is unable to meet the needs of large-scale model test.

3. piston are distributed pressure loader complex structure, high prices, but is also detrimental to the fracture model is embedded in the lead-out.

4. loading mode the majority of the cylinder in the form of + thruster, needs a larger loading space, loading space is limited to the situation of poor adaptability.

Content of the invention

The purpose of the invention is to overcome the above-mentioned disadvantages of the prior art, provides a uniform distribution loading high performance, flexible assembly, the operation is simple, good durability suitable for the geological mechanical model test compound ultra-thin flexible uniform distributed pressure loading device.

To achieve the above object, the invention adopts the following technical scheme:

A geological mechanics model ultra-thin flexible composite used for testing are distributed pressure loading device, comprises a hydraulic cylinder thruster, thruster hydraulic cylinder center of the loading cylinder is provided with a two-way, bi-directional loading cylinder is provided with a connection flange at the top part of the piston, the hydraulic cylinder at the bottom of the pusher is provided with a composite flexible force-transmitting cushion layer.

The thrustor, the hydraulic cylinder comprising an upper plate and a lower plate, a groove-shaped lower plate; loading cylinder is provided with a two-way center of the upper plate and the lower, upper, the lower plate by a plurality of evenly distributed between is connected with the stiffening ribs, stiffening rib is trapezoidal.

The connecting flange is connected with the piston rod by a screw thread, is connected with a bolt hole on the flange.

The hydraulic cylinder under the groove-shaped plate is provided with a composite flexible force-transmitting cushion layer, composite flexible force-transmitting cushion layer through the super glue is fixed on the lower plate.

The composite flexible force-transmitting cushion layer is composed of two layers of different shore hardness of the polyurethane rubber, in shore hardness within 10 degrees of ultra flexibility polyurethane rubber plate, thick 35 mm, external to shore hardness of 30 degrees of flexible polyurethane rubber sheet, the thickness is 15 mm, flexible polyurethane rubber plate is provided with a warp and woof.

Polyurethane ultra flexibility inside of this invention is very soft rubber plate, the load uniformly distributed loading play a pivotal role, the external flexible polyurethane rubber plate comprising a layer of warp and woof, can bear more than 5 MPa high-pressure, high-pressure limits the deformation of the rubber layer under the conditions of the overflowing phenomenon internal ultra flexibility.

The loading system can be applied for the greatest load 40t, model surface of the maximum load for the cross 4 MPa, the cross bias ≤ 5% load, uneven stress on the surface of the model of which the depth is smaller than 100 mm. The Patent refers to the field of flexible uniform loading on the surface of the model, thereby greatly improving loading precision, can be widely applied to various geological mechanics model test loading.

The invention has the following advantages:

1. the device can realize a flexible surface of the model are distributed pressure loading, composite flexible force-transmitting cushion layer superior performance, the load of a large the cross is applied, can be up to 4 MPa, load simplified deviation less than 5%, the depth of the uneven stress on the surface of the model is less than 100 mm.

2. with the hydraulic station and hydraulic automatic control system, to better simulate the original stress conditions of an engineering geology, realize precise control of the stress on the surface of the model, loading deviation ± 0.1 MPa.

3. flexible assembly of the device, the operation is convenient, single loading unit of reasonable size, required to be processed can be of different size according to the load the unit; at the same time the arrangement of the different way can be combined, to realize the gradient loading.

4. the hydraulic cylinder, loading thruster, flexible force-transmitting cushion layer organic fusion together, greatly reduce the size of the model reaction frame, compressing the loading space, save the counter-force frame steel, more powerful adaptability.

5.   the top of the piston is provided with a link flange, through the flange of the loading device can be installed on the model on the reaction frame.

6.   the whole set of the loading device has a simple structure, convenient manufacture, easy to maintain, easy to realize accurate control load, and long service life, is easy to be LED out of the fracture in the model.

Description of drawings

Figure 1 is schematic diagram the center of the cross section structure of this invention;

Figure 2 is a top view of this invention;

Wherein: 1, is connected with the flange, 2, a seal ring, 3, stiffening ribs, 4, loading oil cylinder body, 5, ultra-flexible polyurethane rubber plate, 6, flexible polyurethane rubber plate, 7, bolt hole, 8, an upper plate, 9, an oil outlet, 10, the piston of the oil cylinder, 11, an oil inlet, 12, a lower plate, 13, hydraulic oil cylinder thruster.

Mode of execution

With the embodiment of the Figures and further explanation of the present invention.

As shown in Figure 1, Figure 2 shows, a geological mechanics model ultra-thin flexible composite used for testing are distributed pressure loading device, the thrustor comprises a hydraulic cylinder 13, the thrustor, the hydraulic cylinder 13 is provided with a bi-directional loading cylinder centre, bidirectional loading cylinder is provided with a connection flange at the top part of the piston 1, the thrustor, the hydraulic cylinder 13 is arranged at the bottom of the composite flexible force-transmitting cushion layer. Composite flexible force-transmitting cushion layer through the super glue is fixed on the lower plate 12 is.

The thrustor, the hydraulic cylinder 13 comprises an upper plate 8 and a lower plate 12, lower plate 12 is groove-shaped, is provided with a bi-directional loading cylinder center of the upper plate and the lower, upper, the lower plate by a plurality of evenly distributed between the stiffening ribs 3 is connected with the, stiffening ribs 3 is a trapezoid.

The piston of the oil cylinder 10 with a screw thread the upper end, is connected with the flange 1 is connected with the piston rod by a screw thread, is connected with the flange 1 is provided with bolt holes 7. The piston of the oil cylinder 10 and the loading cylinder body 4 is provided with two sealing ring between 2, by preventing the overflow of the hydraulic oil. Loading oil are respectively provided with the oil inlet of the cylinder block 11 and the outlet port 9.

Composite flexible force-transmitting cushion layer comprises a thruster hydraulic cylinder 13 of groove at the bottom of the lower plate 12 in the two layers of different shore hardness of the polyurethane rubber, in shore hardness within 10 degrees of ultra flexibility polyurethane rubber plate 5, thick 35 mm, external to shore hardness of 30 degrees of flexible polyurethane rubber plate 6, the thickness is 15 mm, flexible polyurethane rubber plate 6 is provided with a warp and woof, can limit the flexible polyurethane rubber ultra-high-pressure conditions 5 overflowing phenomenon of deformation.

The working principle of the invention: with a hydraulic station and the hydraulic automatic control system, hydraulic automatic control system to control the hydraulic oil by the oil inlet 11 into the Figure 1 the loading cylinder shown in the 4 bottom cavity, with the pressure increase, the hydraulic runs the upper part of the oil in the cavity 9, discharge compartment, the piston of the oil cylinder 10 pushes the hydraulic oil cylinder thruster 13 thereupon move forward, and through the connecting flange 1 will force is transmitted to the reaction structure, so as to obtain the counterforce. Counterforce thruster by the hydraulic cylinder 13 the force is transmitted to the ultra flexibility rubber cushion 5 and the flexible rubber Restriant layer 6 is, the final effect on the loading object. By adjusting the pressure of the inlet and outlet of the loading system to adjust the pressure of the object.

The loading system can be applied for the greatest load 40t, model surface of the maximum load for the cross 4 MPa, the cross bias ≤ 5% load, uneven stress on the surface of the model of which the depth is smaller than 100 mm. The invention can be widely applied to various geological mechanics model test loading.