Novel prevent cable pit structure of differential settlement
Technical Field
The invention relates to a novel cable trench structure for preventing uneven settlement, which can be selectively used under the condition of weakening a stratum along a line, so that a cable trench in the weakened stratum and a cable trench at an adjacent section are settled synchronously, and the normal operation of a cable line is prevented from being influenced by the structural damage of the cable trench caused by uneven settlement.
Background
With the acceleration of urbanization progress, the contradiction between the continuously increasing urban power grid demand and the scarce engineering construction space is more and more severe. Therefore, the underground laying mode of the power grid line gradually becomes a trend, however, in a soft soil stratum in the Yangtze river triangular region, a cable tunnel or a cable trench is easy to have large settlement, normal operation of the cable line is influenced, and even potential safety hazards exist.
With the large amount of construction of cable ditches in soft soil foundations, many scholars have studied and analyzed engineering measures for reducing pipe ditch settlement to provide prevention and treatment solutions, the two most representative of which are foundation treatment solutions of a foundation replacement method and a cement mixing pile method. The foundation replacement method mainly adopts the mode of soil replacement, also called soil replacement method, and the process mainly comprises the steps of removing a soft soil layer which is not suitable for serving as a foundation, backfilling the foundation by using other prepared soil layers and gravels in advance, and compacting by using equipment, thereby improving the bearing capacity of the foundation; however, the backfill method is only suitable for certain types of soft soil and engineering conditions requiring a thin soft soil layer and shallow burying depth, and can cause noise pollution to the surrounding environment in the process of mechanically tamping the foundation. The cement mixing pile is an effective form for treating the soft soil foundation, and is characterized in that cement is used as a main agent of a curing agent, and the cement is sprayed into a soil body by using the mixing pile machine and is fully mixed, so that the cement and the soil generate a series of physical and chemical reactions, and the soft soil is hardened to improve the strength of the foundation; although the cement mixing pile method has a remarkable effect of improving the bearing capacity of the foundation, the construction process is complex and is not particularly suitable for frozen soil layers. The two foundation treatment methods increase the engineering earthwork amount to a certain extent, inevitably increase the construction cost and prolong the construction period.
Disclosure of Invention
The invention aims to provide a cable trench structure for preventing uneven settlement, which is used under the working condition that a weak soil foundation is locally arranged along the cable trench structure, so that the settlement difference between a cable pipe trench in a soft soil layer and a cable pipe trench at an adjacent section is reduced, and the slope of a pipeline is controlled within a safe range; in addition, the cable trench device can be used in large scale under the working condition that the soft soil foundation is arranged in a large range along the line, the settlement of the cable trench is reduced, and the normal operation of a cable line is ensured. The construction of the cable tunnel is usually an open cut method, and the device can overcome the problem of uneven settlement of the cable pipe trench caused by sudden change of a pipe trench laying mode, large geological difference along the pipe trench, large difference of new covering soil thickness and the like on the premise of not increasing earth volume, simple construction process and low engineering cost by virtue of a slope releasing process in construction, and reduce the settlement difference of the cable pipe trench along the line.
The invention adopts the following technical scheme:
a novel cable trench structure for preventing uneven settlement comprises a cable trench main body and wing plates arranged on two sides of the cable trench main body; the section of the cable duct main body is rectangular, and the bottoms of the two sides of the cable duct main body protrude outwards; the lower end of the wing plate is connected with the protruding part at the lower end of the cable duct main body through a hinge, and the upper end of the wing plate is connected with the upper end of the cable duct main body through a length-adjustable pull rod; the vertical lateral wall of cable pit main part and the lower extreme contained angle department of pterygoid lamina be equipped with wedge concrete block, its main function does: 1 is used for filling the space between the wing plate and the base and preventing the angle of the wing plate from changing under the combined action of the pull rod and the base; 2, the lower end face of the wing plate is provided with a supporting force, and the hinge is prevented from being sheared and damaged due to stress concentration.
In the technical scheme, furthermore, the wing plates are precast concrete plates added with reinforcing steel bars, the material of the wing plates can also be steel plates, and the surfaces of the wing plates are roughened, so that the contact area between the wing plates and backfill soil is increased, and the final settlement prevention effect of the wing plates is prevented from being reduced due to poor contact between the wing plates and the backfill soil in the later-stage settlement process of the cable trench; wings of different lengths, widths and thicknesses can be designed and produced according to the specific engineering conditions of the cable trench.
Furthermore, two blades of the hinge are respectively fixed with the cable duct main body and the wing plate through bolts, so that the wing plate can rotate by taking the hinge as an axis and can adjust the angle within a certain range. The number of hinges required for the cable trench main body, the number of bolts required for each hinge leaf, the specification size of the hinges, the specification size of the rivets and the like are determined according to the specific conditions of engineering.
Further, the mode of confirming the contained angle between the vertical lateral wall of cable pit main part and the pterygoid lamina does: assuming that the width of the cable trench body is d; the width of the wing plate is L, and the included angle between the vertical side wall of the cable trench main body and the wing plate is theta; d +2 lssin θ; and (3) predicting the settlement amount of the cable trench by means of finite element analysis and other methods, obtaining the required basic width D of the cable trench through inverse calculation, and substituting the basic width D into the formula to obtain the included angle theta between the vertical side wall of the cable trench main body and the wing plate. The area of the cable trench structure is increased by adjusting the included angle between the wing plate and the vertical side wall of the cable trench main body, so that the settlement of the cable trench is controlled, and the purpose of uniform settlement of the cable trench under the condition of weakening the stratum along the line is finally achieved.
Furthermore, the wing plates are installed by adopting a slope-releasing process in open cut construction, so that the problem of uneven settlement of the cable trench is solved on the premise of not increasing the earth volume of the project.
Furthermore, the wedge-shaped concrete blocks can be replaced by other materials, and the included angle of the wedge-shaped concrete blocks can be changed and needs to be kept consistent with the included angle between the wing plate and the vertical side wall of the cable trench main body.
Furthermore, the length-adjustable pull rod is obtained by sleeving a plurality of steel pipes, small holes are drilled in the walls of the steel pipes, and the length is fixed by inserting the fixed inserted rods; the end part of the length-adjustable pull rod is hinged with the wing plate and the cable duct main body.
Furthermore, the cable duct main body comprises an upper cover, a wall body and a base; the upper cover is a precast concrete plate or a steel plate added with reinforcing steel bars; the wall body and the base are of reinforced concrete structures and can be poured at one time; the upper end of the wall body protrudes inwards and is used for placing an upper cover, and the upper cover can be opened and used for people to enter and exit the maintenance equipment; the interior of the wall body is also provided with a fixed bracket for placing various electrical equipment; bolts or rivets can be driven into the outer part of the wall body so as to fix the connecting piece; the base protrudes outwards, bolts or rivets can be driven into the two sides of the base to fix the hinges, and the base and the wing plates jointly form a stress component of the lower soil layer.
In the invention, the wedge-shaped concrete blocks are placed and the pull rods with adjustable installation lengths are mainly used for realizing two purposes. Purpose 1: in the installation stage of the wing plate, the wedge-shaped concrete block and the length-adjustable pull rod can fix the wing plate, so that the included angle between the wing plate and the vertical side wall of the cable trench main body is kept unchanged, therefore, backfilling or other construction can be conveniently and smoothly carried out, and the length-adjustable pull rod is pulled; purpose 2: after the construction, the soil body below the pterygoid lamina produces moment of flexure power to the pterygoid lamina, and moment of flexure power too big can cause the fracture of pterygoid lamina, and the existence of adjustable length pull rod can reduce the moment of flexure power that the pterygoid lamina received, guarantees that the pterygoid lamina does not receive the damage, and adjustable length pull rod receives the pressure this moment. The two ends of the length-adjustable pull rod are connected with the wing plates and the cable duct main body in a hinged mode, and the purpose is to prevent the length-adjustable pull rod from being affected by bending moment.
The cable trench structure has the beneficial effects that:
the settlement amount of the cable trench in the common soil layer foundation and the soft soil layer foundation can be respectively calculated by methods such as finite element analysis, the foundation area required by the cable trench in the soft soil layer can be calculated by reverse calculation in order to keep the settlement amount of the cable trench in the soft soil layer and the common soil layer consistent, the required foundation area can be increased by additionally arranging the wing plate and adjusting the angle of the wing plate, and the synchronous settlement of the cable trench in the weakened stratum and the cable trench in the adjacent good stratum can be finally realized, so that the normal operation of a cable line is prevented from being influenced by the structural damage of the cable trench caused by uneven settlement.
Drawings
FIG. 1 is a schematic structural view (front view) of the device of the present invention after the end of the project;
FIG. 2 is a schematic view (front view) of the overall construction of the apparatus of the present invention in operation;
FIG. 3 is a schematic view of the overall construction of the apparatus of the present invention in construction (left side view);
FIG. 4 is a schematic view (top view) of the overall structure of the device of the present invention;
FIG. 5 is an enlarged view (front view) of section A of the apparatus of the present invention;
FIG. 6 is an enlarged view of section A of the apparatus of the present invention (left side view);
FIG. 7 is an enlarged view (front view) of section B of the apparatus of the present invention;
FIG. 8 is a schematic view (left side view) of the apparatus according to the present invention;
FIG. 9 is a schematic view (perspective) of the overall structure of the device of the present invention;
the hinge comprises a hinge A, a length-adjustable pull rod B, a cable trench main body 1, a wing plate 2, a hinge sheet of a hinge 3, a bolt 4, a bolt a (used for fixing the hinge sheet and the cable trench main body), a wedge-shaped concrete block 5, a bolt 6, a bolt b (used for fixing the wing plate and a connecting piece), a connecting piece 7, a connecting piece a (used for hinging the wing plate and the pull rod), a steel plug 8, a steel pipe C, a reserved small hole 12, a fixed inserted rod 13, a steel plug 14, a steel plug B (used for hinging the cable trench main body and the pull rod) and a bolt 16, a bolt c (used for fixing the connecting piece B and the cable trench main body).
Detailed Description
The invention discloses a novel cable trench structure for preventing uneven settlement, which comprises a cable trench main body 1 and wing plates 2 additionally arranged on two sides of the cable trench main body;
referring to fig. 1 to 9, the protruding part of the lower end of the cable trench body 1 is connected with the lower end of the wing plate 2 through a hinge a, a leaf 3 of the hinge is fixed with the cable trench body 1 and the wing plate 2 through a bolt (a)4, and the wing plate 2 is hinged with the cable trench body 1 through a length-adjustable pull rod B.
Referring to fig. 2-4, assume that the width of the cable trench body 1 is d; the width of the wing plate 2 is L, and the included angle between the wing plate 2 and the vertical side wall of the cable trench main body 1 is theta; d +2 lssin θ. The normal projection area of the cable trench is an important parameter for controlling the settling amount of the cable trench, and the width of the cable trench is positively correlated with the normal projection area of the cable trench under the condition that the length of the cable trench is not changed; in the cable trench engineering construction, when the geological condition shown in fig. 8 is met, the property difference of the foundation soil of the cable trench along the line is large, so that the problem of uneven settlement of the cable trench is caused; the existing finite element analysis software can accurately analyze the settlement rule of the cable trench in different soil layers and can predict the settlement of the cable trench in construction and after construction; the required basic width D of the cable trench can be obtained through inverse calculation, and the included angle theta between the vertical side wall of the cable trench body and the wing plate is obtained through the formula D +2Lsin theta.
In the construction process of the cable trench construction, after the construction of the cable trench main body 1 is completed, the wing plate 2 is additionally arranged according to needs, and as can be seen by referring to fig. 2, the addition of the wing plate 2 can be realized by means of the existing conditions of the open cut method slope-releasing process, and the redundant earthwork construction is not needed.
Referring to fig. 5 and 6, it can be known that the connection between the wing plate 2 and the cable trench main body 1 is mainly completed by the hinge a, the hinge a is mainly fixed to the cable trench main body 1 and the wing plate 2 by the bolt (a)4, and the cable trench main body 1 and the wing plate 2 can be provided with rivet holes during the prefabrication process, so that the workload of the construction site can be reduced; the number of hinges A required by the cable trench with a certain length and the number of bolts (a)4 on each hinge leaf 3 are determined according to the specific conditions of engineering, and the premise is that the hinges and the bolts have enough shear strength, so that the connection quality of the hinges in construction is ensured.
Referring to fig. 2, 4 and 7, the outer end of the wing plate 2 is connected with the cable duct body 1 through a length-adjustable pull rod B made of steel; the length-adjustable pull rod is formed by sleeving a steel pipe (a)9, a steel pipe (b)10 and a steel pipe (c)11 together, the steel pipe (a)9 is hinged with the wing plate 2 through a connecting piece (a)7, the connecting piece (a)7 and the wing plate 2 are fixed through a bolt (b)6, and the connecting piece (a)7 and the steel pipe (a)9 are fixed through a steel plug (a) 8; the steel pipe (c)11 is hinged with the cable trench body 1 through a connecting piece (b)15, the connecting piece (b)15 and the cable trench body 1 are fixed through a bolt (c)16, and the connecting piece (b)15 and the steel pipe (c)11 are fixed through a steel plug (b) 14; small holes 12 are drilled in the pipe bodies of the steel pipe (a)9, the steel pipe (B)10 and the steel pipe (c)11, and the length of the length-adjustable pull rod B is fixed in a mode that a fixed inserting rod 13 is inserted into the small holes 12; the length of the length-adjustable pull rod B is determined according to the specific engineering conditions, and the larger the bending moment force applied to the wing plate 2 is, the smaller the length of the length-adjustable pull rod B is.
Referring to fig. 5, the section of the wedge-shaped concrete block 5 is a right triangle, the included angle of the bottom surface of the wedge-shaped concrete block is consistent with the included angle θ between the wing plate 2 and the vertical side wall of the cable trench body 1, and the θ angle of the wedge-shaped concrete block 5 is placed at the included angle between the cable trench body 1 and the wing plate 2, so as to further prevent the included angle θ between the vertical side wall of the cable trench body and the wing plate from being reduced in the sedimentation process of the cable trench.
Referring to fig. 9, after the angle adjustment of the wing plate 2 is completed, soil backfill construction is performed, and during the backfill construction, soil on the upper portion and the lower portion of the wing plate 2 is guaranteed to be closely compacted, so that the reduction of an included angle theta caused by fluffy soil on the upper portion of the wing plate 2 in the later sedimentation process is prevented, and the function of preventing sedimentation of the wing plate is weakened.