Abstract:
A method for constructing a large-span station by two-wing open type semi-covered excavation and semi-reverse construction, is divided into three stages of excavation. First, excavate a first-stage inner small foundation pit, then excavate a second-stage annular foundation pit within the first-stage retaining piles and outside the range of the first-stage inner small foundation pit, and finally excavate a third-stage semi-covered excavation foundation pit below the first-stage inner small foundation pit and the second-stage annular foundation pit. By setting graded retaining piles, middle upright post piles, middle top plates, local waist beams and local concrete supports in the soil-rock combination strata, so that the force transfer between the foundation pit enclosure and the station main body structures and the underlying rock layer is clear and reliable, and a stable frame structure is achieved.
Abstract:
The present disclosure provides a structural engineering dominated geotechnical structured permanent supporting system and a design method, and belongs to the technical field of underground structures. Through the technical solutions, the structural engineering dominated geotechnical structured permanent supporting system comprises a supporting structure designed on the basis of the partial coefficient of a permanent load, the supporting structure is connected to frame columns of a main structure through a plurality of connecting members arranged at intervals, and a partition wall for blocking soil mass is arranged between every two adjacent frame columns to form a permanent supporting system only bearing soil pressure in the horizontal direction of the supporting structure. When the system is designed, the combined action generated after the main structure and the supporting structure are connected is considered, so that the use of materials is reduced, and the cost is reduced.
Abstract:
A rock head for use with an auger borer to bore a passageway through a body of soil and rock and simultaneously laying a pipe in that bored passageway. The rock head has a base connectable to the leading end of the auger. A plurality of movable mounts are provided on the base and a roller cone is secured to each movable mount. A spring is disposed between the movable mount and the base. The spring is compressed as the movable mount pivots the roller cones inwardly toward a central region of the base. This reduces the diameter of the rock head so that it can travel through the bore. Each movable mount is provided with at least one wheel so that it can ride smoothly through the bore. When the rock head exits the pipe, the springs automatically pivots each roller cone outwardly so that at least a portion thereof is disposed beyond the outermost edge of the base. In this second position, the rock head has a greater diameter than the pipe bore and therefore it cannot travel therethrough. When the auger is withdrawn through the pipe, the movable mounts pivot the roller cones from the second position back to the first position, thereby causing the rock head to collapse to a diameter sufficiently small enough to travel back through the pipe.
Abstract:
In a method of constructing a reinforced concrete work such as a road tunnel, an underground gallery or a tunnel for an underground railway, there is first excavated an open trench 62 in which there are then placed, consecutively and contiguously, prefabricated hollow concrete frame element 4, the external faces of which have reinforcements 5. A filler concrete 18 is then poured so as to cover the joints between elements and to cooperate with the reinforced concrete of the frame elements and with the reinforcements so as to construct, by consecutive stages and rapidly, a monolithic work. The strength of this monolithic work is appreciably greater than the respective strengths of the prefabricated elements initially placed and of the filler concrete. Finally the trench is filled. Preferably the external reinforcements 5 of the frame elements are such as to cooperate with the filler concrete which is subsequently placed round the elements.
Abstract:
A bridge system uses foundation structures that are formed of the combination of a metal-frame structure and cast-in-place concrete. The metal-frame structure of the foundation is capable of supporting bridge units before pouring of concrete.
Abstract:
The invention relates to an installation (10) for making a continuous wall in ground (S), the installation comprising: an excavation machine (14) having a frame (16) with a bottom end (16b); determination means (80) for periodically determining the offset between the frame and a first screen while making a second screen in the ground juxtaposed with the first screen; and correction means (50) for periodically correcting the position of the frame (16) so as to reduce the offset as determined by the determination means between the frame (16) and the first screen (E1), and maintain overlap between the longitudinal side of the frame and the longitudinal side of the first screen in such a manner that the second screen is secant with the first screen (E1) over the entire length of the shorter of the first and second screens, thereby forming the wall that is continuous.
Abstract:
A method for making a wall in soil. The method may include forming a trench in the soil; filling the trench with a self-hardening material; supplying at least one prefabricated element that has two plates connected together by a connection member; and positioning the prefabricated element in the trench filled with the self-hardening material.