A composite support structure

Abstract

This invention relates to the field of retaining structures and discloses a composite retaining structure, including an upper retaining and a lower retaining. The upper retaining supports the fill soil, and the lower retaining supports the excavated slope. A counterweight is provided on the side of the upper retaining near the fill soil, which can withstand the vertical load on the upper part of the fill soil. Anchors are provided on the lower retaining, which can be anchored into hard rock strata. The anchors include multiple anchoring units, which are set at different heights on the lower retaining. Each anchoring unit includes two prestressed anchor cables with different inclination angles. The inclination angles of the prestressed anchor cables in all anchoring units on the same anti-slide pile increase sequentially from top to bottom to solve the problem that the anchor cables are easily sheared in the fill area.

Description

Technical Field

[0001] This invention relates to the field of retaining structures, and more specifically to a composite retaining structure. Background Technology

[0002] The interface between the weak structural layer and the hard rock layer of soil and rock is called the soil-rock interface. For unstable slopes with steep soil-rock interfaces, one end of an anchor cable is usually inserted through the weak structural layer of soil and rock and anchored into the hard rock layer within the soil and rock to connect the weak structural layer and the hard rock layer together. This changes the stress state of the soil and rock on the slope and improves the integrity and strength of the unstable soil and rock on the slope.

[0003] For slopes that are partially excavated and partially filled, with significant sliding along the rock-soil interface and a planned building above, the slope includes both the excavated slope and the fill. The excavated slope is the side of the weak structural layer closest to the excavation area. In the fill area, anchor cables are prone to shearing due to settlement of the newly filled fill. If a large retaining wall is used, it is costly and bulky, and the excavation working face of the retaining wall foundation is large, which can easily disturb the rock and soil, destroy the stability of the existing rock and soil structure, and cause large-scale landslides. If a composite form of retaining wall plus anti-slide piles is used, although the working face of the anti-slide piles is small, when the rock and soil in the excavation area are excavated, the anti-slide piles lose the rock and soil support on the side closest to the excavation area, the stress structure of the anti-slide piles changes, the stability decreases, the design and construction requirements are high, and it is not conducive to safety control. Summary of the Invention

[0004] The present invention aims to provide a composite support structure to solve the problem that anchor cables are easily sheared in embankment areas.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a composite retaining structure, comprising an upper retaining and a lower retaining, wherein the upper retaining supports the fill soil and the lower retaining supports the excavated slope, a counterweight platform is provided on the side of the upper retaining near the fill soil, the counterweight platform can bear the vertical load on the upper part of the fill soil, and anchors are provided on the lower retaining, the anchors can be anchored into hard rock strata, the anchors include multiple anchoring units, different anchoring units are set at different heights of the lower retaining, each anchoring unit includes two prestressed anchor cables with different inclination angles, and the inclination angles of the prestressed anchor cables of all anchoring units on the same anti-slide pile increase sequentially from top to bottom.

[0006] The beneficial effects of this plan are:

[0007] 1. Compared to directly setting anchor cables in the fill area, this scheme eliminates the anchor cables in the fill area and sets a counterweight platform on the side of the upper support close to the fill soil. The vertical load of the fill soil acts on the counterweight platform, forcing the center of gravity of the upper support to move towards the fill soil side, thus increasing the stability of the upper support.

[0008] 2. Since the vertical load of the fill soil acts on the counterweight platform, it generates a first eccentric force at the connection between the upper and lower supports. In this scheme, anchors are installed on the lower support and anchored in the hard rock layer, which in turn generates pressure on the lower support. This pressure generates a second eccentric force at the connection between the upper and lower supports. The bending moments generated by the first and second eccentric forces are in opposite directions and can thus cancel each other out.

[0009] 3. The pressure remaining after the second eccentric force cancels out the first eccentric force, and cancels out the lateral earth pressure on the excavation slope. After the soil and rock in the excavation area are excavated, the lower retaining loses the soil and rock support on the side close to the excavation area. The stress structure of the lower retaining changes little and the stability is high.

[0010] 4. Prestressed anchor cables consist of a free section and an anchorage section. The anchorage section is anchored into a hard rock layer within the soil. The end of the free section furthest from the anchorage section is the prestressing tensioning end. Since the two prestressed cables in the same anchorage unit are set at the same height (i.e., the prestressing tensioning ends are at the same height), the greater the difference in inclination angle between the two prestressed anchor cables, the farther the distance between the anchorage sections, the smaller the overlap of the anchorage range of the two prestressed anchor cables, the larger the total anchorage range of the two prestressed anchor cables, and the better the anchorage effect.

[0011] 5. Due to the steepness of the soil-rock interface, the smaller the inclination angle of the prestressed anchor cable, the closer the angle between the prestressed anchor cable and the soil-rock interface becomes to perpendicular. For the same length, the prestressed anchor cable can be anchored deeper into the hard rock layer, resulting in better anchoring. However, when the soil-rock strength of the excavated slope is poor, the load from the fill soil will increase the settlement of the excavated slope, causing deformation of the prestressed anchor cable and disrupting the connection between the free section and the anchored section. The larger the inclination angle of the prestressed anchor cable, the smaller the shear force generated by the vertical load from the excavated slope settlement on the prestressed anchor cable. In this scheme, after the excavated slope is excavated, to offset the first eccentric force, sufficient second eccentric force is mainly provided by the upper prestressed anchor cable with a smaller inclination angle. After the excavated slope settles, the prestressed anchor cable with the smaller inclination angle deforms, increasing the density of the excavated slope, which can provide sufficient reaction force to the counterweight platform, thus offsetting part of the first eccentric force. The second eccentric force provided by the lower prestressed anchor cable with a larger inclination angle is sufficient to meet safety requirements.

[0012] Preferably, as an improvement, the lower support includes anti-slide piles and a panel between the anti-slide piles. The anti-slide piles are rectangular, and anchors are installed on the anti-slide piles. With this configuration, compared to circular piles, the rectangular piles have a larger contact area with the anchors, resulting in less pressure exerted by the anchors on the lower support. After the soil and rock in the excavated area are removed, the panel can provide support against the lateral forces of the soil and rock between the anti-slide piles.

[0013] Preferably, as an improvement, there are multiple anti-slide piles, with a counterweight retaining wall as the upper support. The counterweight retaining wall and the anti-slide piles are connected by a stepped pile cap, with the lower step on the side of the pile cap closest to the backfill. This arrangement transfers the load of the counterweight retaining wall to the multiple anti-slide piles through the pile cap; the stepped pile cap prevents the counterweight retaining wall from sliding horizontally.

[0014] Preferably, as an improvement, the anti-slide pile is provided with a corbel at its upper end, and the upper surface of the corbel is connected to the pile cap. This arrangement increases the contact area between the anti-slide pile and the pile cap, and the corbel disperses the reaction force of the anti-slide pile on the pile cap to the pile cap, preventing the reaction force from damaging the pile cap.

[0015] Preferably, as an improvement, the prestressed anchor cable is fitted with a sleeve. With this configuration, drilling is required before installing the prestressed anchor cable. To prevent hole collapse after drilling in weak structural layers, this solution places a sleeve inside the hole during drilling. The sleeve provides support to the inner wall of the hole, allowing the anchor cable to smoothly pass through the sleeve within the hole.

[0016] Preferably, as an improvement, mortar is filled between the sleeve and the prestressed anchor cable. The sleeve has several sections, and an inner convex ring is provided on the inner wall of the end of the sleeve away from the anti-slip pile. The mortar between the sleeves overflows from the sleeve to form an anti-pull-out ring.

[0017] This setting will produce the following beneficial effects:

[0018] 1. During the grouting process, the mortar flows from the top of the uppermost sleeve to the bottom of the lowermost sleeve. The mortar flows naturally downwards without being pressurized, so it does not exert significant downward pressure on the inner convex ring. The mortar level rises from the lowest point of the sleeve. When the level reaches the position between the two sleeves, due to the inner convex ring, the water flow cross-section suddenly decreases, and the water pressure suddenly increases. The mortar lifts the lower surface of the inner convex ring, which in turn lifts the upper sleeve, creating a gap between the sleeves. The mortar overflows from the gap, forming an anti-pull-out ring. After the mortar level submerges the inner convex ring, the amount of mortar above the inner convex ring increases, and the downward pressure exerted by the mortar on the inner convex ring gradually increases, causing the gap to gradually close.

[0019] 2. If only one sleeve is used, the sleeve is too long and requires a huge crane to drop the sleeve into the hole, making construction difficult. Therefore, it is necessary to use multiple shorter sleeves in combination. The anti-pull-out ring can strengthen the connection between the sleeves after it solidifies.

[0020] 3. The pull-out ring is perpendicular to the force direction of the prestressed anchor cable, which increases the contact area between the soil and the overall structure, thereby increasing the friction between the soil and the overall structure and improving the stability of the prestressed anchor cable structure.

[0021] 4. The position between the two sleeves is the weak point of the sleeve, and the pull-out ring fills the gap between the sleeve and the hole near the weak point, reducing the settlement of the weak point. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of Example 1;

[0023] Figure 2 This is a three-dimensional isometric view of the sleeve in Example 2. Detailed Implementation

[0024] The following detailed description illustrates the specific implementation method:

[0025] The reference numerals in the accompanying drawings include: counterweight retaining wall 1, counterweight platform 101, anti-slide pile 201, anchor pier 202, panel 203, corbel 204, prestressed anchor cable 205, sleeve 206, inner convex ring 207, pile cap 3, excavation area 401, fill soil 402, design ground line 403, original ground line 404, soil-rock interface 405, weak structural layer 406, hard rock layer 407.

[0026] Example 1

[0027] Example 1 is basically as follows Figure 1 As shown: A composite support structure, comprising an upper support and a lower support.

[0028] The upper support is for the fill soil 402. The design ground line 403 is above the fill soil 402, and the original ground line 404 is below the fill soil 402. The upper support is a counterweight retaining wall 1. A counterweight platform 101 is provided on the side of the counterweight retaining wall 1 near the fill soil 402. The counterweight platform 101 can bear the vertical load on the upper part of the fill soil 402.

[0029] The lower retaining structure supports the excavated slope, which is the rock and soil on the right side of the lower retaining structure. The lower retaining structure includes multiple anti-slide piles 201 and a panel 203 between the multiple anti-slide piles 201. The anti-slide piles 201 are rectangular piles, and anchors 201 are installed on the anti-slide piles 201. The anchors 201 include two anchoring units, which are located at different heights of the lower retaining structure. Each anchoring unit includes an anchor block 202 and two prestressed anchor cables 205. The prestressed anchor cables 205 include a free section and an anchoring section. The free section is the part of the prestressed anchor cable 205 within the weak structural layer 406, and the anchoring section is the part of the prestressed anchor cable 205 within the hard rock layer 407. In this section, the interface between the weak structural layer 406 and the hard rock layer 407 is the soil-rock interface 405. The anchorage section is longer than ten meters, and the specific length is determined according to the site conditions. The anchor pier 202 is cast on the anti-slide pile 201. The left ends of the two prestressed anchor cables 205 are tensioned on the anchor pier 202, and the right ends of the two prestressed anchor cables 205 pass through the weak structural layer 406 and are anchored into the hard rock layer 407. The inclination angles α of the two prestressed anchor cables 205 are different. The α of the prestressed anchor cables 205 of all anchorage units on the same anti-slide pile 201 increases sequentially from top to bottom. In this embodiment, the α is 20°, 25°, 30° and 35° respectively.

[0030] The upper end of the anti-slide pile 201 is provided with a corbel 204, and the upper surface of the corbel 204 is connected to a pile cap 3. The pile cap 3 is stepped, and the side of the pile cap 3 closest to the fill soil 402 is a low step. The lower surface of the counterweight retaining wall 1 is connected to the pile cap 3. The counterweight retaining wall 1 bears the horizontal load of the fill soil. The pile cap 3 transfers the horizontal load of the counterweight retaining wall 1 to multiple anti-slide piles 201 and prestressed anchor cables, and then transfers it to deeper hard rock layers through the prestressed anchor cables.

[0031] The specific implementation steps are as follows:

[0032] 1. Construct anti-slide piles 201, corbels 204, pile caps 3, and counterweight retaining walls 1 in sequence. Pile caps 3 are set in a stepped shape to prevent counterweight retaining walls 1 from sliding horizontally. Corbels 204 disperse the reaction force of anti-slide piles 201 on pile caps 3 to pile caps 3, preventing the reaction force from damaging pile caps 3.

[0033] 2. The area above the original ground line 404 and the designed ground line 403 is the excavation area 401. The excavation area 401 is excavated using the reverse construction method. The upper part of the excavation area 401 is excavated, and two prestressed anchors 205 of the first anchoring unit are constructed, with α being 20° and 25° respectively. The prestressed anchors 205 provide a second eccentric force relative to the foundation 3 to counteract the first eccentric force.

[0034] 3. Excavate the lower part of the excavation area 401 and construct the two prestressed anchor rods 205 of the second anchoring unit, with α being 30° and 35° respectively.

[0035] 4. After the soil and rock structure in the excavation area has stabilized, fill soil 402 is backfilled to the design elevation. The vertical load of fill soil 402 acts on the counterweight platform 101 of the counterweight retaining wall 1, generating the first eccentric force relative to the foundation 3, which forces the center of gravity of the counterweight retaining wall 1 to move towards the fill soil 402 side, increasing the stability of the counterweight retaining wall 1.

[0036] 5. When the soil and rock stability is poor or the weather is severe, the two prestressed anchor rods 205 of the second anchoring unit have a larger inclination angle, and the vertical load generated by the settlement of the excavation slope has a smaller shear force on the prestressed anchor cable 205, making the prestressed anchor cable 205 less prone to deformation.

[0037] Example 2

[0038] Example 2 is based on Example 1: the prestressed anchor cable 205 has several outer sleeves such as Figure 2 The sleeve 206 shown is filled with mortar between the sleeve 206 and the prestressed anchor cable 205. The sleeve 206 has several sections. The inner wall of the sleeve 206 away from the anti-slip pile 201 is provided with an inner convex ring 207. The mortar between the sleeves 206 overflows from the sleeve to form an anti-pull-out ring.

[0039] The specific implementation steps are as follows:

[0040] 1. Drill holes in the rock and soil, insert sleeves 206 into the holes one by one, and insert prestressed anchor cables 205.

[0041] 2. Grouting begins. The mortar flows from the inner top of the uppermost sleeve 206 to the inner bottom of the lowermost sleeve 206. The mortar flows naturally downwards without being pressurized, so it does not exert significant downward pressure on the inner convex ring 207. The mortar level rises from the lowest point of the sleeve 206. When the level reaches the position between the two sleeves 206, the cross-sectional area of ​​the mortar suddenly decreases due to the inner convex ring 207, and the hydraulic pressure of the mortar suddenly increases. The mortar lifts the lower surface of the inner convex ring 207, which in turn lifts the upper sleeve 206, creating a gap between the sleeves 206. The mortar overflows from the gap, forming an anti-pull-out ring. After the mortar level submerges the inner convex ring 207, the amount of mortar above the inner convex ring 207 increases, and the downward pressure exerted by the mortar on the inner convex ring 207 gradually increases, causing the gap to gradually close.

[0042] 3. The position between the two sleeves 206 is the weak point of the sleeve 206, and the anti-pull ring fills the gap between the sleeve 206 and the hole near the weak point, reducing the settlement of the weak point.

[0043] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A composite support structure, characterized in that: It includes an upper support and a lower support. The upper support supports the fill soil, and the lower support supports the excavated slope. The upper support has a counterweight platform on the side closest to the fill soil, which can withstand the vertical load on the upper part of the fill soil. The lower support is equipped with anchors that can be anchored into hard rock strata. The anchors consist of multiple anchoring units, which are set at different heights in the lower support. Each anchoring unit includes two prestressed anchor cables with different inclination angles. The inclination angles of the prestressed anchor cables in all anchoring units on the same anti-slide pile increase sequentially from top to bottom. The prestressed anchor cable includes a free section and an anchoring section, with the anchoring section being longer than ten meters. Within the weak structural layer of the soil and rock, the prestressed anchor cable is fitted with a sleeve; mortar is filled between the sleeve and the prestressed anchor cable, the sleeve has several sections, and the inner wall of the sleeve at the end away from the anti-slide pile is provided with an inner convex ring, and the mortar between several sleeves overflows from the sleeve to form an anti-pull-out ring.

2. The composite support structure according to claim 1, characterized in that: The lower support includes anti-slide piles and a panel between the anti-slide piles. The anti-slide piles are rectangular piles, and the anchors are set on the anti-slide piles.

3. The composite support structure according to claim 2, characterized in that: There are multiple anti-slide piles, and the upper support is a counterweight retaining wall. The counterweight retaining wall and the anti-slide piles are connected by a pile cap. The pile cap is stepped, and the side of the pile cap closest to the backfill soil is a lower step.

4. The composite support structure according to claim 3, characterized in that: The anti-slide pile is equipped with a corbel at the top, and the upper surface of the corbel is connected to the pile cap.

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