[0022] See figure 1 , The construction method of the present invention for treating road bridge head bumping includes roadbed treatment, base course treatment and pavement construction, and specifically includes the following steps.
[0023] Step A. Use plain soil or light-weight materials to fill the back of the platform in layers. The compaction thickness of each layer should not exceed 20cm, and the compactness is greater than 95% at the best moisture content, and the filling height is 2~3m and the subgrade elevation The surface is tamped with a strong tamping machine to form a stable subgrade 70 on the back of the platform. The light-weight material refers to a filler with a low density. Due to the low density of the filler, the settlement caused by the weight of the bridge head is small, which can greatly reduce the pressure applied to the foundation, thereby helping to solve the technical problem of the bridge head jumping.
[0024] The compactness of the compaction is greater than 100% at the optimal moisture content. In the prior art, low density is a fundamental problem that causes bridgehead jumping. There are two main reasons for the low compactness. One is that the compaction strength is low, and the other is that large compaction equipment is not applicable in the area close to the back wall of the platform, and it is close to the vertical wall. The opposite wall causes damage and damages the foundation of the bridge, thus causing an under-compaction state in the area where the bridge head is connected. In the process of testing the compactness of the present invention, it is shown that the compactness of the subgrade constructed on site can reach or even exceed 100%. The main reason is that the standards in the existing specifications are low, and ordinary technicians are bound by the design specifications. breakthrough. In the present invention, the ground pressure of the strong tamping machine to the roadbed is stronger than 1.4 MPa, and it can avoid damage to the vertical wall. The main principle is: through the vibration of the vibrating hammer to achieve continuous strong vibration of the roadbed, to achieve the resonance efficiency of the soil particles, use the resonance principle to apply strong compaction work to the soil foundation under the state of soil particles floating and slip, to achieve the rapid stability of the roadbed; Acting on the pressure equalizing convex strip in the middle of the bottom of the bottom plate to evenly disperse the force of the vibrating hammer mechanism, and at the same time cut off the side pressure of the vibrating hammer mechanism on the soil through the arc groove strip at the edge to avoid causing the edge of the bridge Excessive lateral pressure damages the bridge.
[0025] The specific structure of a strong tamping machine is given in this embodiment, see image 3 with 4 The structure of the dynamic compaction machine includes a vibrating mechanism with a vibrating hammer 2, a drive motor 5, and a vibration exciter 4. There are convex strips evenly distributed on the bottom surface of the vibrating hammer 2. The convex strip structure includes two types: one One type is the pressure-breaking convex strip 3-2 that is set at the edge of the bottom surface of the vibrating hammer and the acting surface is a concave arc surface. One is uniformly distributed in the middle of the bottom surface of the vibrating hammer and the acting surface is a convex arc surface. The pressure equalizing protruding strip 3-1 and the breaking pressure protruding strip 3-2 cut off the external pressure generated by the vibrating hammer 2 on the soil. The structure also includes a guide bracket 1 and a first guide wheel group 6A and a second guide wheel group 6B arranged on the vibrating mechanism. The vibration mechanism uses the first guide wheel group 6A and the second guide wheel group 6B and the guide bracket 1 The vertical beams form a vertical sliding fit. The vibration exciter 4 is arranged in the inner cavity of the vibrating hammer 2, and the driving motor 5 is arranged at the top end of the vibrating hammer 2 and is connected to the vibration exciter 4 by means of a matching transmission mechanism.
[0026] Using the above-mentioned powerful tamping machine, at a distance of about 20cm from the standing wall of the back of the table, start to apply pressure to the subgrade, and apply pressure for 10s at each point, about 100 times. Hit point 7 uses a plum-shaped layout, such as figure 2 Shown. Since the tamping machine is relatively close to the back wall 20, a larger ramming force will damage the back wall and cause cracks. Therefore, during construction at this location, the bottom surface of the vibrating hammer of the tamping machine used is improved, that is, the edge of the vibrating hammer is provided with a pressure-breaking rib 2 that cuts off the lateral pressure, so that the force of the vibrating hammer 1 is not Will spread to the back of the stage 20.
[0027] Step B: Manufacture a reinforced cement concrete slab 50 with the same width as the bridge, and layer it with the base material on the abutment back roadbed to form a rigid-flexible transition layer with reinforced cement concrete slab.
[0028] The strength of the reinforced cement concrete slab is not less than 20MPa, and it adopts a single-layer Φ12 rebar welded wire mesh, the width is the same as that of the bridge (culvert), and the length is 20-30m.
[0029] The rigid-flexible transition layer can be single-layer, double-layer, triple-layer or multilayer. figure 1 It is a schematic diagram of the structure when the rigid-flexible transition layer is three layers. It can be seen that when the rigid-flexible transition layer is three layers, the rigid-flexible transition layer is divided into an upper base layer 40, a middle base layer and a lower base layer 60, and the reinforced cement concrete slab 50 is located in the middle. The thickness of the base layer is the thickness of the middle base layer designed in accordance with relevant specifications.
[0030] First of all, according to the highway asphalt pavement construction technical specification JTG F40-2004, the lower base layer is mixed, paved and compacted. Then follow the highway cement concrete pavement construction technical specification (JTJ034-2000) to carry out the construction and laying of reinforced cement concrete slab; reserve a 2~5cm gap between the reinforced cement concrete slab and the vertical wall 20 on the back of the abutment, and fill it with 70# asphalt sand Tamped, the asphalt sand 30 can not only play the function of permanently sealing water, but also an elastic body between different materials to prevent damage to the structure. Finally, the construction of the upper base layer was carried out in accordance with the technical specification for highway asphalt pavement construction JTG F40-2004. The rigidity of the rigid-flexible transition layer of the invention is between the bridge deck and the ordinary roadbed, forming a rigid-flexible transition section. The tar sand is a mixture formed by mixing sand and a certain proportion of asphalt.
[0031] When the rigid-flexible transition layer has two layers, it is divided into an upper base layer and a lower base layer. The reinforced cement concrete slab is located on the lower base layer, and its thickness is the thickness of the lower base layer designed according to relevant specifications.
[0032] When the base layer in the rigid-flexible transition layer is a single layer, the rigid-flexible transition layer is composed of a reinforced cement concrete slab and a single base layer, and the reinforced cement concrete slab is located between the single base layer and the roadbed and has a thickness of not less than 18 cm. The thickness is the thickness designed in accordance with relevant specifications.
[0033] Step C. Simultaneously carry out road construction on the bridge deck and the rigid-flexible transition layer to form an integrated road structure.
[0034] During asphalt pavement construction, it is forbidden to stop, turn around, or connect at the junction of the bridge deck and the road base. The pavement joints should avoid the bridge head, and the construction specifications are the same as the existing construction specifications.
[0035] In summary, the design and construction of the present invention are based on the existing design specifications and construction specifications, without additional support, the design specifications and construction are simple, mainly by setting up a rigid-flexible transition layer and tamping the roadbed can effectively solve the problem of bridgehead jumping technical challenge.
