Open excavation construction method for transverse connection channel of shield tunnel
Technical Field
The invention belongs to the technical field of tunnel transverse connection channel construction, and particularly relates to an open cut construction method of a shield tunnel transverse connection channel.
Background
At present, according to the design specifications of the existing highways, municipal and subway tunnels and the requirements of related technical standards, communication channels are required to be arranged between double-hole tunnels, the arrangement type and the spacing are respectively 1, the first civil engineering work of the highway tunnel design specification JTG3370.1-2018, the 4.5.1, the arrangement type and the spacing are defined as ①, the spacing is preferably 250m and is not more than 350m, ②, the arrangement spacing is preferably 750m and is not more than 1000 m.2, the design specifications of urban underground road engineering specification CJJ221-2015, the 8.3.5, the arrangement type and the spacing are defined as ①, the transverse pedestrian evacuation channels or the transverse pedestrian evacuation channels are arranged, the spacing between ②, the spacing between underground roads and the transverse pedestrian evacuation channels is preferably 250 m-300 m, the arrangement type and the spacing between 250 m-8.3.6, the arrangement type and the spacing between ①, the urban underground tunnels of two or three types of motor vehicles are preferably 500-500, the arrangement type and the spacing between 500, the transverse underground vehicle channels are preferably 500, the spacing between 500, the transverse underground vehicle access channels are 500, the arrangement type and the spacing between 500, the transverse evacuation channels are preferably 1000, the arrangement type and the spacing between 800-1000-year-on-year-on-year-on-year-on-year-on-for the underground tunnel design specifications of underground tunnel for the same-on-underground vehicle-on-by-under-for the same-underground tunnel design specifications of underground vehicle-on-by-underground vehicle-underground tunnel design specification, the same tunnel design specification of underground vehicle-for the same tunnel design specification of underground vehicle-underground vehicle.
The existing shield tunnel connection channel construction method comprises a mine method, a pipe jacking method and a shield method, and different methods have different characteristics and applicability. 1) A mine method: the technology of the contact channel constructed by the mine method is relatively mature, the application is extremely wide, and the mine method is mostly adopted for construction particularly in the construction of the contact channel of the urban subway tunnel in China. But the defects are obvious, such as low construction efficiency, poor economy and high safety risk, and meanwhile, the reinforcement effect of the soil around the contact channel has great influence on the success of construction. At present, ground reinforcing methods, in-hole grouting reinforcing methods and freezing methods are used for soil body reinforcing methods, wherein particularly the freezing method has the defects of numerous control influence factors of construction effects, great safety risks, long construction period, high cost, prominent operation and maintenance diseases, and many cases of construction failures caused by the freezing method are adopted in China. 2) Pipe jacking method: the pipe jacking method is used as a modern underground pipeline construction method, and during construction, the pipe is pressed into a soil layer through a force transmission jacking iron and a guide rail and a hydraulic jack supported on a back wall, and soil on the front side of the pipe is dug and carried away. And after the first pipe joint is completely jacked into the soil layer, connecting the second pipe joint behind the first pipe joint and jacking continuously, and jacking the first pipe joint in such a way to make a joint, thereby constructing a channel. The pipe jacking method has small influence on the environment, high mechanization degree and short construction period, but special equipment and a jacking rack need to be equipped during construction, the internal space of the finished structure of the main line shield tunnel is occupied, the influence on construction organization and construction period is large, and the stress and the influence on the structure are not clear in the construction process. At present, the domestic application cases are few. 3) A shield method: the shield method is adopted to directly cut and break the segments of the main line tunnel structure and apply the segments to the contact channel, and has the advantages of strong stratum adaptability, high mechanization degree, long tunneling distance, short construction period and the like. Meanwhile, the shield construction method also needs to be matched with a special small shield machine, a muddy water treatment system and a backup rack, occupies larger internal space of the finished structure of the main line shield tunnel, and has larger influence on construction organization and construction period. On the other hand, the construction of the small shield machine has the engineering risks of starting and receiving, and the construction cost is relatively high.
At present, no case report is found in the construction of a transverse connection channel of a main line shield tunnel section by adopting an open excavation method.
Disclosure of Invention
The invention provides an open excavation construction method for a transverse connection channel of a shield tunnel, and aims to solve the problems that the construction cost of the conventional transverse connection channel of the shield tunnel is high and the engineering risk is relatively high.
The invention adopts the following technical scheme:
an open excavation construction method for a transverse connection channel of a shield tunnel comprises the following construction steps:
step one, constructing a first underground continuous wall in a direction parallel to the tunnel line position and a second underground continuous wall in a direction vertical to the tunnel line position around the left line shield tunnel and the right line shield tunnel in the range of the horizontal communication channel planned to be excavated and extending to the left line shield tunnel and the right line shield tunnel, and enclosing to form a closed annular shaft;
cutting and breaking the second underground continuous wall in the direction perpendicular to the tunnel line position in the left line shield tunnel and the right line shield tunnel by using a shield machine, and erecting assembled shield segment structures in the left line shield tunnel and the right line shield tunnel;
step three, performing foundation pit support on the foundation pit dug by the ground surface downwards in the area surrounded by the first underground continuous wall and the second underground continuous wall layer by layer until the bottom elevation position of the transverse communication channel;
fourthly, dismantling the shield segments on the left line and the shield segments on the right line in the left line shield tunnel and the right line shield tunnel in the surrounding area and above the bottom elevation of the transverse communication channel;
constructing a main tunnel frame structure and a transverse connection channel inner frame structure in the left-line shield tunnel and the right-line shield tunnel;
and sixthly, backfilling earthwork above the main tunnel frame structure and the transverse connection channel frame structure, removing the foundation pit support, recovering the ground in the current situation, and completing construction of the transverse connection channel.
The invention has the following advantages:
the method of the invention is adopted to carry out the construction of the transverse connection channel of the shield tunnel, which not only can meet the requirement of the double-hole tunnel for arranging the transverse connection channel specified by the tunnel design specification, but also can reduce the risk and the construction cost of the connection channel adopting the mining method, the pipe jacking method and the shield method, and provides a good choice for the safe and effective construction of the transverse connection channel of the shield tunnel.
Description of the drawings:
FIG. 1 is a schematic plan view of the present invention.
Fig. 2 is a schematic cross-sectional structure of the present invention.
FIG. 3 is a schematic diagram of the structure of the invention in a vertical section.
Reference numerals:
1 underground diaphragm wall, 1-1 underground diaphragm wall I, 1-2 underground diaphragm wall II, 2 left line shield tunnel, 3 right line shield tunnel, 4 shield segment structure, 4-1 left line lower shield segment, 4-2 left line upper shield segment, 5-1 right line lower shield segment, 5-2 right line upper shield segment, 6 main tunnel frame structure, 7 transverse communication channel, 8 foundation pit support, 8-1 foundation pit support first cross brace, 8-2 foundation pit support Nth cross brace, 9 on-site ground surface support
The specific implementation mode is as follows:
the following further describes the embodiments of the present invention with reference to the drawings.
As shown in fig. 1, 2 and 3, an open excavation construction method for a transverse communication channel of a shield tunnel comprises the following construction steps:
step one, constructing an underground continuous wall 1-1 in a direction parallel to the tunnel line position and an underground continuous wall 2 in a direction vertical to the tunnel line position in the surrounding of the left line shield tunnel 2 and the right line shield tunnel 3 in the range of the horizontal communication channel 7 to be excavated and extending to the left line shield tunnel 2 and the right line shield tunnel 3, and enclosing to form a closed annular shaft, wherein the role of the closed annular shaft is to form a soil retaining and water stopping structure which is beneficial to forming later-stage excavation safety and stability, and the enclosed annular shaft is shown in the attached drawing 1;
secondly, cutting and breaking the underground continuous wall II 1-2 in the direction vertical to the tunnel line position in the left line shield tunnel 2 and the right line shield tunnel 3 by using a shield machine, erecting an assembled shield segment structure 4 in the left line shield tunnel 2 and the right line shield tunnel 3, and resisting the action of soil layer pressure and some special loads, and referring to the attached drawing 1;
step three, constructing foundation pit supports 8 layer by layer in the areas surrounded by the underground continuous walls I1-1 and the underground continuous walls II 1-2 from the ground surface to the bottom elevation position of the transverse communication channel 7, and referring to the attached figure 2;
fourthly, dismantling the shield segments 4-2 on the left line and the shield segments 5-2 on the right line in the shield tunnels 2 and 3 on the left line and the shield segments 5-2 on the right line in the surrounding area, wherein the shield segments are positioned above the bottom elevation of the transverse communication channel 7, and refer to the attached drawing 2;
constructing a main tunnel frame structure 6 in the left shield tunnel 2 and the right shield tunnel 3 and an inner frame structure in the transverse communication channel 7, and referring to the attached drawing 2;
and sixthly, backfilling earthwork above the main tunnel frame structure 6 and the transverse connection channel 7 frame structure, removing the foundation pit support 8, recovering the existing ground 9, and completing construction of the transverse connection channel 7, wherein the construction is shown in the attached drawing 3.
The underground continuous wall is constructed by adopting a conventional method, and the following construction method can be adopted: excavating along the periphery of a foundation pit under the condition of slurry wall protection to form a groove with a certain length, then placing the manufactured reinforcement cage into the groove section, performing underwater concrete pouring by adopting a conduit method to form a unit wall section, and mutually connecting all the wall sections by adopting a specific joint mode (such as a joint made of a joint pipe or a joint box) to form a continuous underground reinforced concrete wall.