CN-122013755-A - Assembled diaphragm wall Fe-SMA pre-tightening type connecting structure and construction method thereof

CN122013755ACN 122013755 ACN122013755 ACN 122013755ACN-122013755-A

Abstract

The invention discloses an assembled diaphragm wall Fe-SMA pre-tightening type connecting structure and a construction method thereof, wherein the structure comprises a vertical supporting unit, a horizontal pre-tightening force generating unit, a positioning unit and a power supply unit; the vertical supporting unit consists of screw steel and is placed in the butt joint groove, the horizontal pretightening force generating unit is an Fe-SMA rib welded on the screw steel, the positioning unit is a positioning device welded on the screw steel and is a ring-shaped clamp made of Fe-SMA, the power supply unit is an iron plate, a power wire and a power generation device which are arranged on the upper part of the screw steel, and the pretightening type connecting device radially contracts after power is applied, so that active pretightening of the joint is realized. The invention realizes the active regulation and control of the connection performance through the electric heating pre-tightening process with adjustable parameters, and can flexibly set the pre-tightening force, thereby obviously improving the node connection rigidity and the horizontal bearing capacity of the assembled diaphragm wall and effectively guaranteeing the overall stability and long-term safety of the deep foundation pit engineering.

Inventors

HUANG LIJI
HUANG LEI
LI ZHENGZHANG
TAI YANG
XING YONGCHENG
Yuan Jianghuai
LIU XIAODONG
LIU MINGHU
DENG HUIYUAN
MU BAOGANG
ZHU HONG
Gui Zheyi
XIE HAODONG

Assignees

东南大学
中交公路规划设计院有限公司

Dates

Publication Date: 20260512
Application Date: 20260324

Claims (10)

1. The Fe-SMA pre-tightening type connecting structure of the assembled diaphragm wall is characterized by comprising a prefabricated concave wall (5), a prefabricated convex wall (6) and a pre-tightening type connecting device, wherein the prefabricated concave wall (5) and the prefabricated convex wall (6) are horizontally connected through the pre-tightening type connecting device; The pre-tightening type connecting device comprises a vertical supporting unit, a horizontal pre-tightening force generating unit, a positioning unit and a power supply unit; the vertical supporting unit comprises two pairs of screw steels (1) which are vertically arranged in parallel and are used for being placed in strip-shaped grooves (7) of the prefabricated concave wall (5) and the prefabricated convex wall (6); The horizontal pretightening force generating unit comprises a horizontal Fe-SMA rib (2), two ends of the Fe-SMA rib (2) are respectively welded on two deformed steel bars (1) positioned in the same strip-shaped groove (7), the two deformed steel bars are upwards equidistantly arranged from the bottom of the deformed steel bars (1), the distance is 1500mm, and a grid frame is formed by the two deformed steel bars (1); The positioning unit comprises positioning devices (3), wherein the positioning devices (3) are respectively welded on the outer surface of the deformed steel bar (1), and are upwards and equidistantly arranged from the bottom of the deformed steel bar (1) at a distance of 1200mm; the power supply unit comprises an iron plate (4) and a power supply device, wherein the iron plate (4) is fixed at the upper end of the screw steel (1) and is used for supplying power to the Fe-SMA rib (2) and the positioning device (3); After pouring and curing of the grouting material are completed, the grouting material is electrified, the Fe-SMA rib (2) and the positioning device (3) heat at the same time, and continuous normal compressive stress is formed between the prefabricated wallboards at the two sides due to the physical characteristics of heat shrinkage and cold expansion of the Fe-SMA, so that active pretension of the joint is realized.
2. The Fe-SMA pre-tightening connection structure for the fabricated diaphragm wall, which is disclosed in claim 1, is characterized in that the diameter of the screw-thread steel (1) is 20-32mm, the screw-thread steel (1) is HRB400 grade, the screw-thread steel (1) is suitable for a wall body with the thickness of 800-1000mm, the distance between the screw-thread steel (1) and the edge of the wall body is not less than 100mm, and the length of the screw-thread steel (1) is 150mm longer than the height of the prefabricated concave wall (5) so as to facilitate the installation of a power supply unit.
3. The prefabricated ground wall Fe-SMA pre-tightening connecting structure according to claim 1 is characterized in that the diameter of the horizontal Fe-SMA rib (2) is 16-22mm, the length L1 of the horizontal Fe-SMA rib is 50d2, and d2 is the diameter of the horizontal Fe-SMA rib.
4. The fabricated diaphragm wall Fe-SMA pre-tightening connection structure according to claim 3, wherein the Fe-SMA is an intelligent material which takes iron as a matrix, is doped with manganese and silicon components, realizes a shape recovery function through thermoelastic martensitic transformation, has a transformation temperature adjusted within a range of 100-200 ℃, has a tensile strength of 500MPa, and needs to exert a tensile force on Fe-SMA ribs (2) at normal temperature so as to generate permanent plastic elongation.
5. The fabricated diaphragm wall Fe-SMA pre-tightening connection structure according to claim 1, wherein the positioning device (3) is made of Fe-SMA with the thickness of 6mm, the width of 20mm and the length of not more than 220mm, and is made into an annular clamp, the initial inner diameter of the annular clamp is matched with the diameter of the threaded steel (1), the length L2 of an extension arm of the positioning device (3) is smaller than the width of a strip-shaped groove (7) of the prefabricated concave wall (5), the extension arm points to the center direction of the strip-shaped groove (7), the positioning device (3) is conveniently inserted into the strip-shaped groove (7) of the prefabricated concave wall (5) and the prefabricated convex wall (6), and a tensile force is required to be applied to the extension arm of the Fe-SMA clamp at normal temperature, so that permanent plastic elongation is generated.
6. The Fe-SMA pre-tightening type connecting structure for the fabricated diaphragm wall is characterized in that the iron plates (4) are galvanized iron plates (4) with the dimensions of 100mm multiplied by 6mm, two iron plates (4) are arranged at the upper end of each screw steel (1), and the two iron plates (4) are fixed at the top ends of the screw steels (1) through bolts.
7. The assembled diaphragm wall Fe-SMA pre-tightening type connecting structure according to claim 1 is characterized in that the power wire is a high-temperature-resistant flexible cable, the nominal sectional area of a wire core is 50mm < 2 > -95 mm < 2 >, the wire core is coated with a high-temperature-resistant insulating layer and a flame-retardant sheath, and the end part of the power wire is connected with an iron plate (4) through a copper connecting terminal and a bolt and is provided with insulation protection.
8. The prefabricated ground wall Fe-SMA pre-tightening connection structure of claim 1, wherein the power supply unit is an adjustable low-voltage high-current direct-current power supply, the output voltage range is 0-50V, the output current capacity is not less than 350A, the power supply unit is provided with a constant-current or constant-voltage output mode, and the current and time can be precisely controlled according to a preset program, so that the stable regulation and control of the heating process of the Fe-SMA rib (2) and the positioning device (3) are realized.
9. A construction method based on the assembled diaphragm wall Fe-SMA pre-tightening type connecting structure as set forth in claims 1-8, which is characterized by comprising the following steps: Step S1, selecting deformed steel bars (1) according to the thickness of a designed wall, wherein the length of the deformed steel bars is generally longer than the height of a prefabricated wall, the distance between the deformed steel bars (1) is 40d1, d1 is the diameter of the deformed steel bars (1), selecting horizontal Fe-SMA bars (2), applying tension to the Fe-SMA bars (2) at normal temperature to enable the Fe-SMA bars to generate permanent plastic elongation, fixing the two deformed steel bars (1) in parallel, the distance between the deformed steel bars is 50d2 of the horizontal Fe-SMA bars (2), respectively welding three horizontal Fe-SMA bars (2) between the two deformed steel bars (1), forming a grid frame with a vertical supporting unit from the bottom of the deformed steel bars at equal intervals, then arranging a positioning device (3), finally installing a power supply unit, fixing four iron plates (4) on the top ends of the two deformed steel bars (1) respectively through bolts, and reserving wiring holes on the iron plates (4); S2, manufacturing a prefabricated concave wall (5), namely reserving three vertical butt joint grooves at vertical joints of the wallboard, wherein the cross sections of two strip-shaped grooves (7) close to the edges are round corner rectangles, and the depth penetrates through the height of the wallboard; S3, manufacturing a prefabricated convex wall (6), namely reserving two vertical strip-shaped grooves (7) and a middle butt joint boss (61) at the vertical joint of the wallboard, wherein the cross sections of the two strip-shaped grooves (7) close to the edge are round corner rectangles, and the depth penetrates through the height of the wallboard; s4, on-site installation and positioning, namely hoisting the prefabricated concave wall (5) and the prefabricated convex wall (6) to a designed position in sequence, enabling a middle butt joint groove (51) of the prefabricated concave wall (5) to be matched with a middle butt joint boss (61) of the prefabricated convex wall (6), enabling a strip-shaped groove (7) of the prefabricated convex wall (6) to be aligned with the strip-shaped groove (7) of the prefabricated concave wall (5) to form a continuous groove cavity, stably inserting a pre-tightening connecting device into the strip-shaped groove (7), Step S5, grouting filling and curing, namely continuously injecting slurry into the strip-shaped groove (7) by adopting high-temperature-resistant micro-expansion high-strength grouting slurry until the top of the groove overflows with uniform slurry; S6, activating pretightening force, namely reserving a wiring hole on an iron plate (4), switching on a power supply, slowly raising output current, enabling the pre-buried Fe-SMA rib (2) and a positioning device (3) to uniformly heat to 100-120 ℃ and keeping the constant temperature state for 30-60 minutes, and enabling the Fe-SMA rib (2) and the positioning device (3) to radially shrink due to the physical characteristics of thermal shrinkage and cold expansion of Fe-SMA, so that the whole grid frame generates horizontal tensile stress, and further forming continuous normal compressive stress between the prefabricated wallboards on two sides through the bonding friction effect of grouting materials and groove walls, thereby realizing active pretightening of joints; And S7, cooling to form permanent pre-tightening force, namely cutting off a power supply after heating is finished, and slowly cooling the whole connecting structure to the ambient temperature in a natural environment to form long-term effective pre-tightening force.
10. The construction method according to claim 9, wherein the high-strength grouting material resistant to high temperature and micro-expansion in the step S5 is aluminate cement-based high-temperature resistant mortar, has a 28-day compressive strength of not less than 50MPa, has a long-term resistant temperature of not less than 150 ℃, and has a micro-expansion characteristic.

Description

Assembled diaphragm wall Fe-SMA pre-tightening type connecting structure and construction method thereof Technical Field The invention relates to the technical field of geotechnical engineering and underground structural engineering, in particular to an assembled diaphragm wall Fe-SMA (iron-based shape memory alloy) pre-tightening type connecting structure and a construction method thereof. Background With the development of modern urban underground space in a deeper and wider direction, the assembled underground continuous wall technology has become the mainstream choice of deep foundation pit supporting engineering due to the remarkable advantages of the assembled underground continuous wall technology in terms of construction efficiency, quality consistency and environmental friendliness. However, efficient and reliable connection between prefabricated parts is always a core challenge limiting the technology to develop towards high performance and long service life, wherein the mechanical and sealing properties of the vertical joints are particularly critical. In current engineering practice, the mainstream connection technology of the vertical seam has corresponding limitations. The traditional steel bar lap joint grouting mode is highly dependent on field operation quality, has large performance discreteness, and essentially belongs to a passive bearing system, and is difficult to perform active performance adjustment or compensation during the service period of the structure. Although the mechanical connection such as a high-strength bolt is convenient to install, the requirements on prefabrication precision and installation centering are extremely strict, the rigidity mutation of a node area is easy to occur, and the node area is often a weak link of a structure. Although the pre-buried prestress connection can actively introduce compressive stress, the pre-buried prestress connection faces the practical difficulties of complex process, high pore channel reservation precision, difficult quantitative evaluation of long-term stress loss, limited field tensioning operation space and the like. In summary, the prior art generally faces a common problem that it is difficult to implement active and controllable mechanical property enhancement on the connection node after the structure is integrally formed and bears the load. In the face of the severe requirements of complex geological conditions and deep and large foundation pits, the development of a novel intelligent connection technology capable of realizing 'assembly and use as well as enhancement as required' has become an urgent need for pushing the technical progress and engineering innovation of assembled underground structures. Disclosure of Invention The invention aims to provide an assembled diaphragm wall Fe-SMA pre-tightening type connecting structure and a construction method thereof, so as to realize active and adjustable pre-tightening reinforcement of vertical joint joints after wallboard assembly and grouting complete solidification, thereby remarkably improving the overall rigidity, horizontal bearing capacity and long-term working performance of the joints. In order to achieve the above purpose, the invention provides an assembled type ground continuous wall electric heating pre-tightening type connecting structure applying Fe-SMA, which comprises a prefabricated concave wall, a prefabricated convex wall and a pre-tightening type connecting device, wherein the prefabricated concave wall and the prefabricated convex wall are horizontally connected through the pre-tightening type connecting device; The pre-tightening type connecting device comprises a vertical supporting unit, a horizontal pre-tightening force generating unit, a positioning unit and a power supply unit; The vertical supporting unit comprises two pairs of screw steels which are vertically arranged in parallel and are used for being placed in the strip-shaped grooves of the prefabricated concave wall and the prefabricated convex wall; The horizontal pretightening force generating unit comprises a horizontal Fe-SMA rib, two ends of the Fe-SMA rib are respectively welded on two screw steels positioned in the same strip-shaped groove, the two screw steels are upwards equidistantly arranged from the bottom of the screw steels, the interval is 1500mm, and a grid frame is formed by the two screw steels; the positioning units comprise positioning devices which are respectively welded on the outer surface of the screw-thread steel and are upwards and equidistantly arranged from the bottom of the screw-thread steel, and the interval is 1200mm; the power supply unit comprises an iron plate fixed at the upper end of the screw-thread steel and a power supply device, and is used for supplying power to the Fe-SMA rib and the positioning device; and because of the physical characteristics of Fe-SMA thermal shrinkage and cold expansion, continuous normal compressive stress is formed between