CN212452680U - Isolation supporting structure of highway tunnel foundation pit of underpass pipeline - Google Patents

Abstract

The utility model relates to the technical field of foundation pit support in engineering construction, in particular to an isolation support structure of a road tunnel foundation pit with a pipeline passing through the lower part, wherein the foundation pit area corresponding to the pipeline is an interruption area, the isolation support structure comprises a pair of underground continuous walls, and the pair of underground continuous walls are respectively disconnected in the interruption area; concrete supports are arranged in the foundation pit of the interruption area corresponding to each pipeline, and the concrete supports are arranged in parallel to the pipelines; a pair of partition walls are distributed between the pair of underground continuous walls to divide the foundation pit into an isolation operation area and an external operation area, an MJS gravity type retaining wall is distributed on the side wall of the foundation pit in the interruption area, and cast-in-place pile walls are uniformly distributed along the outer side walls of the pair of continuous walls corresponding to the isolation operation area; an MJS pit bottom reinforcing wall is horizontally distributed at the bottom of a foundation pit of the isolated operation area; and a rotary spraying pit bottom reinforcing wall is arranged at the bottom of the foundation pit in the external operation area. The utility model provides a wear the pipeline down, on wear subway tunnel's highway tunnel foundation's isolation and support problem, guarantee going on smoothly of excavation.

Description

Isolation supporting structure of highway tunnel foundation pit of underpass pipeline

Technical Field

The utility model relates to a technical field of excavation supporting among the engineering construction, the isolation supporting construction of the highway tunnel foundation ditch of pipeline is worn under concretely relates to.

Background

With the progress of urbanization, urban space resources are more and more in shortage, in order to deal with the traffic congestion phenomenon caused by rapid population density and perfect urban function construction, more and more traffic main roads are transferred to the underground, and because the traffic main roads are often positioned in urban areas with dense buildings, adverse effects on the surrounding environment cannot be avoided when road foundation pits are excavated. In view of the complicated arrangement of the urban pipelines at present, the post-construction foundation pit inevitably passes through the pipeline construction, and great inconvenience is brought to the support of the foundation pit structure and the protection of the pipelines.

At present, for the post-construction foundation pit to penetrate through the existing pipeline engineering, a pipeline moving and modifying measure is mostly adopted. The pipeline is changed to avoid the selection problem of a foundation pit supporting structure in the foundation pit excavation process, the safety of the foundation pit is guaranteed, and meanwhile, the influence of excavation unloading on the existing pipeline can be avoided, so that the pipeline is widely applied to the engineering. However, for the condition that the foundation pit transversely penetrates through the pipeline, the length of the pipeline exposed on the foundation pit is long, other land space resources are inevitably occupied by adopting a moving and modifying measure, the construction period of the project is prolonged, the project economy is increased, the cost control is not facilitated, and the resource waste is also caused by the fact that the original pipeline is buried in the underground soil layer; meanwhile, for the important pipelines required by urban life, the movement and the modification will certainly influence the life of residents, and inconvenience is brought to the life of the residents.

Although the engineering case and the supporting technology for in-situ protection of the pipeline penetrating through the foundation pit already exist, the in-situ protection of the pipeline still remains, and the self safety of the foundation pit support is neglected.

Because the foundation pit and the surrounding environment are a complex community and the foundation pit and the existing pipeline are inseparable whole bodies, the design of a supporting system for coordinately controlling the foundation pit and the pipeline is particularly important.

SUMMERY OF THE UTILITY MODEL

The utility model provides a problem among the background art provides an isolation protection support system and construction method who wears existing pipeline under highway tunnel foundation ditch, and this method not only can satisfy the excavation supporting requirement, plays the effect of the existing pipeline of protection moreover, the utility model discloses specific technical scheme is:

an isolation supporting structure of a highway tunnel foundation pit with a downward-penetrating pipeline and a construction method are provided, the foundation pit 1 is a highway tunnel construction foundation pit, the existing pipeline 2 penetrates through the foundation pit 1, the distance between the top plate of the highway tunnel 5 and the pipeline 2 is more than or equal to 0.5m, the area of the foundation pit 1 corresponding to the pipeline 2 is an interruption area 7, a subway tunnel 6 transversely penetrates through the soil body below the foundation pit 1,

the isolation supporting structure comprises a pair of underground continuous walls 3 distributed along two side walls of the foundation pit 1, and the pair of underground continuous walls 3 are respectively disconnected in an interruption area 7; concrete supports 11 are arranged in the foundation pit 1 of the interruption area 7 corresponding to each pipeline 2, and the concrete supports 11 are arranged in parallel to the pipelines 2;

a pair of partition walls 4 are arranged between the pair of underground continuous walls 3, the pair of partition walls 4 are vertically arranged in the foundation pit 1 at intervals, the foundation pit 1 is divided into an isolation operation area 9 and an external operation area 10, the corresponding area of the foundation pit 1 between the pair of partition walls 4 is the isolation operation area 9, and the interruption area 7 is positioned in the middle of the isolation operation area 9;

an MJS gravity type retaining wall 14 is distributed on the side wall of the foundation pit 1 of the interruption area 7, and cast-in-place pile walls 13 are uniformly distributed along the outer side walls of a pair of continuous walls corresponding to the isolation operation area 9;

an MJS pit bottom reinforcing wall 12 is horizontally distributed at the bottom of the foundation pit 1 of the isolation operation area 9, and the thickness of the MJS pit bottom reinforcing wall 12 is more than or equal to 5 m; and a pair of partition walls 4 corresponding to the bottom of the foundation pit 1 of the external operation area 10 are horizontally provided with a rotary spraying pit bottom reinforcing wall 17, and the thickness of the rotary spraying pit bottom reinforcing wall 17 is more than or equal to 4 m.

Furthermore, the breaking positions of the pair of underground continuous walls 3 are respectively provided with a folding wall 8, the folding walls 8 are correspondingly and vertically connected with the end parts of the continuous walls, and the transverse extension length of each folding wall 8 is 1.0-1.5 m; the depth of the cast-in-place pile wall 13 is greater than that of the MJS gravity type retaining wall 14, and the pile bodies of the cast-in-place pile wall 13 are connected through occlusion.

Further, the lateral extension of the MJS gravity retaining wall 14 is greater than 2 times the longitudinal extension of the interrupted area 7, and the thickness of the MJS gravity retaining wall 14 is greater than the longitudinal extension of the interrupted area 7.

Further, the concrete supports 11 are flush with the upper ends of the folding walls 8, concrete diagonal braces 15 are arranged between the side walls of the partition walls and the inner side walls of the corresponding continuous walls, and concrete cross braces 16 are arranged between a pair of continuous walls adjacent to the diagonal braces.

The utility model has the advantages of as follows:

(1) aiming at the existing pipeline in the foundation pit, the utility model discloses utilize the division wall to divide the foundation pit into a plurality of operation regions, wherein in the isolation operation region further divide the foundation pit that the pipeline corresponds into the interrupt area, evade the foundation pit easily to destroy the link through adjusting the division wall position, make the protection of existing pipeline work become independent construction operation region, reduce the construction disturbance scope greatly, weaken other operation region construction mutual influence, effectively control the foundation pit, the deformation of existing pipeline and the soil body around the foundation pit;

concrete supports are uniformly distributed in the interruption area corresponding to each pipeline, a cast-in-place pile wall is distributed outside a continuous wall of the isolation operation area, an MJS gravity type retaining wall is distributed on the side wall of a foundation pit of the interruption area, and meanwhile, a folding wall is arranged at the end part of the continuous wall, so that the isolation supporting structure is continuous and complete, the effect of dispersing soil load can be achieved, and the stress deformation of the existing pipeline is reduced; the MJS gravity type retaining wall formed by the MJS construction method reinforces the soil mass outside the isolated operation area, is beneficial to enhancing the soil retaining and water stopping effects of the supporting structure, increases the strength of the soil mass outside the pit, and reduces the displacement of the soil mass, thereby achieving the purpose of controlling the deformation.

(2) Aiming at the problem that the underground tunnel is transversely crossed below a highway tunnel foundation pit, the utility model discloses use the MJS worker method to consolidate the foundation pit bottom soil layer of the isolation operation area, form the horizontal MJS pit bottom reinforced wall, and the thickness of the MJS pit bottom reinforced wall is more than or equal to 5m, be favorable to reducing the earth excavation unloading effect in the pit, weaken the influence of the subsequent subway tunnel construction on the upper underground passage and the existing pipeline;

the foundation pit bottom soil layer of the foundation pit in the external operation area is reinforced by adopting a high-pressure jet grouting pile reinforcing method to form a horizontal jet grouting pit bottom reinforced wall, the thickness of the reinforced wall is more than or equal to 4m, the continuity of pit bottom reinforcement is guaranteed, uneven stress of the foundation pit is avoided, and meanwhile, the jet grouting reinforcement technology is also favorable for reducing the cost.

Drawings

Fig. 1 is a top view of the isolation protection support structure of the present invention;

fig. 2 is a schematic perspective view of the isolation protection support structure of the present invention;

fig. 3 is a schematic view of the pit bottom of the isolation protection support structure of the present invention;

FIG. 4 is a sectional view of the isolation protection support structure of the present invention taken along line 1-1;

fig. 5 is a schematic perspective view of an isolation operation area of the isolation protection support structure of the present invention;

fig. 6 is a side view of an isolation operation area of the isolation protection support structure of the present invention;

in the figure: 1, foundation pit; 2-a pipeline; 3-a pair of underground continuous walls; 4-a pair of dividing walls; 5-a road tunnel; 6-subway tunnel; 7-a break zone; 8-folding the wall; 9-isolating the operation area; 10-an outer working area; 11-concrete support; 12-MJS pit bottom reinforced wall; 13-pouring pile walls; 14-MJS gravity wall; 15-concrete diagonal bracing; 16-concrete waling; 17-jet grouting pit bottom reinforcing wall.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the invention, are given by way of illustration only.

Example 1

See fig. 1~ 6, the utility model discloses a wear highway tunnel foundation's of pipeline isolation supporting construction down, foundation ditch 1 is highway tunnel 5 construction foundation ditch 1, and foundation ditch 1 transversely extends length 30m, excavation depth 12m, wears existing pipeline 2 under foundation ditch 1, and the roof of highway tunnel 5 and the interval of pipeline 2 are 0.7m, 2 diameters 1.8m of pipeline and 1.4m pipeline 2 buried depth 2.3 m.

The area of the foundation pit 1 corresponding to the pipeline 2 is an interruption area 7, the longitudinal extension length of the interruption area 7 is 7.2m, a subway tunnel 6 transversely penetrates through the soil body below the foundation pit 1, the diameter of the subway tunnel 6 is 6.6m, and the buried depth is 22.8 m.

The isolation supporting structure comprises a pair of underground continuous walls 3 which are distributed along two side walls of the foundation pit 1, wherein the thickness of each continuous wall is 0.6m, and the depth of each continuous wall is 18 m.

The pair of underground continuous walls 3 are respectively disconnected in the interruption area 7, concrete supports 11 are arranged in the foundation pit 1 of the interruption area 7 corresponding to each pipeline 2, and the concrete supports 11 are arranged in parallel to the pipelines 2.

A pair of partition walls 4 are arranged between the pair of underground continuous walls 3, the pair of partition walls 4 are vertically arranged in the foundation pit 1 at intervals, and the thickness of each partition wall is 0.6m and the depth is 18 m.

The foundation pit 1 is divided into an isolation operation area 9 and an external operation area 10 by the pair of partition walls 4, the corresponding area of the foundation pit 1 between the pair of partition walls 4 is the isolation operation area 9, the interruption area 7 is positioned in the middle of the isolation operation area 9, the longitudinal extension length of the isolation operation area 9 is 38m, and the water level is reduced to 1m of the pit bottom.

An MJS gravity type retaining wall 14 is arranged on the side wall of the foundation pit 1 of the interruption area 7, the thickness of the MJS gravity type retaining wall 14 is 8.5m, the longitudinal extension length is 15m, and the depth is 25m, cast-in-place pile walls 13 are uniformly distributed along the outer side walls of a pair of continuous walls corresponding to the isolation operation area 9, the diameter of each cast-in-place pile of the cast-in-place pile walls 13 is 850mm, and the pile depth is 25 m.

An MJS pit bottom reinforcing wall 12 is horizontally distributed at the bottom of the foundation pit 1 of the isolation operation area 9, and the thickness of the MJS pit bottom reinforcing wall 12 is 5 m; and a pair of partition walls 4 corresponding to the bottom of the foundation pit 1 of the external operation area 10 are horizontally provided with a rotary spraying pit bottom reinforcing wall 17, and the thickness of the rotary spraying pit bottom reinforcing wall 17 is 4 m.

The broken parts of the pair of underground continuous walls 3 are provided with folding walls 8, the thickness of each folding wall 8 is 0.6m, the depth of each folding wall 8 is 18m, the end parts of the folding walls 8 and the end parts of the continuous walls are correspondingly and vertically connected, and the longitudinal extension length of each folding wall 8 is 1.5 m; the vertical depth of the cast-in-place pile wall 13 is 1.2 times of the depth of the MJS gravity type retaining wall 14, and the pile bodies of the cast-in-place pile wall 13 are connected through occlusion.

The longitudinal extension of the MJS gravity retaining wall 14 is greater than 2 times the longitudinal extension of the interrupted area 7, and the thickness of the MJS gravity retaining wall 14 is greater than the longitudinal extension of the interrupted area 7.

The concrete supports 11 are flush with the upper ends of the folded walls 8, concrete inclined struts 15 are arranged between the side walls of the partition walls and the inner side walls of the corresponding continuous walls, and concrete cross struts 16 are arranged between a pair of continuous walls adjacent to the inclined struts.

Example 2

The construction method of the isolation and support structure of the foundation pit 1 of the highway tunnel 5 based on the underpass pipeline 2 of the embodiment 1 specifically comprises the following steps:

step (1): simultaneously pouring a pair of underground continuous walls 3, a folding wall 8 and a dividing wall in the foundation pit 1, wherein the thickness and the depth of the folding wall 8, the dividing wall and the pair of underground continuous walls 3 are the same, the thickness is 0.6m, and the depth is 18 m;

the area of the foundation pit 1 corresponding to the pipeline 2 is an interruption area 7, the longitudinal extension length of the interruption area 7 is 7.2m, the pair of continuous walls is disconnected in the interruption area 7, the end parts, corresponding to the interruption area 7, of the pair of continuous walls are provided with folding walls 8, the folding walls 8 are vertically connected with the end parts, corresponding to the continuous walls, of the folding walls 8, and the transverse extension length of the folding walls 8 is 1.5 m.

Step (2): the side wall of the foundation pit 1 corresponding to the interruption area 7 is reinforced with a soil body by adopting an MJS construction method to form an MJS gravity type retaining wall 14, the transverse extension length of the MJS gravity type retaining wall 14 is more than 2 times of the longitudinal extension length of the interruption area 7, the thickness of the MJS gravity type retaining wall 14 is more than the longitudinal extension length of the interruption area 7, and the depth of the MJS gravity type retaining wall 14 is more than the depth of a pair of underground continuous walls 3; the pressure of construction cement paste in the MJS construction method is more than or equal to 40MPa, the water cement ratio is 1:1, the air pressure is 1.05MPa, and the formed MJS gravity type retaining wall 14 has the thickness of 8.5m, the length of 15m and the depth of 25 m.

And (3): and (3) constructing cast-in-place bored piles along the outer side walls of the pair of continuous walls corresponding to the isolation operation area 9 to form a cast-in-place pile wall 13, wherein the cast-in-place bored piles adopt an occlusion construction technology to ensure the quality of the cast-in-place pile wall 13, so that pile bodies of the cast-in-place pile wall 13 are connected in an occlusion manner, and the depth of each pile body is 1.5 times that of the pair of underground continuous walls 3.

And (4): reinforcing a pit bottom soil layer of a foundation pit 1 of an isolation operation area 9 by adopting an MJS construction method to form a horizontal MJS pit bottom reinforced wall 12, wherein the thickness of the MJS pit bottom reinforced wall 12 is 5m, the cement paste pressure of the MJS construction method is more than or equal to 30MPa, the water cement ratio is 1:1, and the air pressure is 0.8 MPa;

reinforcing a pit bottom soil layer of a foundation pit 1 of a 10 foundation pit in an external operation area by adopting a high-pressure rotary jet grouting pile reinforcing method to form a horizontal rotary jet grouting pit bottom reinforcing wall 17 with the thickness of 4m and the length of 4-5 m, wherein the high-pressure rotary jet grouting pile reinforcing method adopts 42.5-grade portland cement, the water cement ratio is 1.0, the air pressure is 0.6-0.8 Mpa, and the water pressure is 30-35 Mpa;

and (5): a concrete support 11 is constructed corresponding to one side of each pipeline 2, the height of the concrete support 11 is consistent with that of the folded wall 8, each concrete support 11 is arranged parallel to the corresponding pipeline 2,

a concrete diagonal brace 15 is constructed between the outer side wall of the partition wall and the inner side wall of the corresponding continuous wall, and a concrete cross brace 16 is constructed between a pair of continuous walls adjacent to the diagonal brace;

and (6): after the construction of the isolation supporting structure is completed and the strength meets the design strength requirement, dewatering the isolation operation area 9 in an in-pit dewatering mode, wherein the water level surface is lower than the excavation surface at the bottom of the foundation pit 1 of the isolation operation area 9 by more than 0.5m after dewatering;

and adopting a layered and block excavation mode, and sequentially excavating earthwork from the middle part to two sides of the isolation operation area 9, wherein the excavation thickness of each layer is less than or equal to 2m, and the block excavation length is less than or equal to 5m until the excavation of the foundation pit 1 of the isolation operation area 9 is completed.

And (7): lowering the water level of the external operation areas 10 on the two sides, wherein the water level is lower than the excavation surface of the bottom of the foundation pit 1 of the external operation areas 10 by more than 0.5m after lowering the water level;

and excavating the external operation area 10 by adopting a layered and partitioned excavation mode, wherein the excavation thickness of each layer is less than or equal to 2m, and the partitioned excavation length is less than or equal to 5m until the excavation of the foundation pit 1 of the external operation area 10 is completed.

And (8): and (3) removing the pair of partition walls 4 and the concrete diagonal braces 15 to ensure that the whole foundation pit 1 is through, and backfilling earthwork after the construction of the highway tunnel 5 in the foundation pit 1 is finished.

The utility model provides a keep apart the problem of strutting of highway tunnel foundation ditch with wear the pipeline down, specific as follows:

(1) the utility model discloses utilize the division wall to separate into a plurality of operation intervals with foundation ditch 1, wherein divide foundation ditch 1 that pipeline 2 corresponds into interrupt region 7 in isolation operation region 9 further, evade foundation ditch 1 breakable link through adjusting the division wall position, make existing pipeline 2 protection work become independent construction operation interval, reduce construction disturbance range greatly, weaken other operation interval construction mutual influence, effectively control foundation ditch 1, the deformation of existing pipeline 2 and the soil body around foundation ditch 1;

concrete supports 11 are uniformly distributed in the interruption region 7 corresponding to each pipeline 2, a cast-in-place pile wall 13 is distributed outside a continuous wall of the isolation operation region 9, an MJS gravity type retaining wall 14 is distributed on the side wall of the foundation pit 1 of the interruption region 7, and a folding wall 8 is arranged at the end part of the continuous wall, so that the isolation supporting structure is continuous and complete, the effect of dispersing soil load can be achieved, and the stress deformation of the existing pipeline 2 is reduced; the MJS gravity type retaining wall 14 formed by the MJS construction method reinforces the soil outside the isolated operation area 9, is beneficial to enhancing the soil retaining and water stopping effects of the supporting structure, increases the strength of the soil outside the pit, and reduces the displacement of the soil, thereby achieving the purpose of controlling the deformation.

(2) The utility model discloses use the MJS worker method to the foundation 1 pit bottom soil layer reinforcement of foundation ditch of isolation operation area 9, form horizontal MJS pit bottom reinforced wall 12, and MJS pit bottom reinforced wall 12 thickness is more than or equal to 5m, is favorable to reducing the interior earthwork excavation unloading effect of hole, weakens the influence of follow-up subway tunnel 6 construction to upper portion underground passage and existing pipeline 2;

the foundation layer of the foundation pit 1 in the foundation pit 10 in the external operation area is reinforced by adopting a high-pressure jet grouting pile reinforcement method to form a horizontal jet grouting pit bottom reinforced wall 17, the thickness of the reinforced wall is larger than or equal to 4m, the continuity of pit bottom reinforcement is guaranteed, the uneven stress of the foundation pit 1 is avoided, and meanwhile, the jet grouting reinforcement technology is also favorable for reducing the cost.

(3) The MJS construction method is used in the MJS pit bottom reinforced wall 12 and the MJS gravity type retaining wall 14, the MJS construction method can carry out construction in all directions at any angle, the construction quality is controllable, the reliability is high, and the influence of the construction process on the surrounding environment is small. The MJS construction method is used for reinforcing soil outside the isolated operation area 9, so that the soil retaining and water stopping effects of the supporting structure are enhanced, the strength of the soil outside the pit is increased, and the displacement of the soil is reduced, thereby achieving the purpose of controlling deformation; the reinforcement of the pit bottom of the isolation operation area 9 is beneficial to reducing the unloading effect of earth excavation in the pit and weakening the influence of the subsequent construction of the subway tunnel 6 on the upper underground passage and the existing pipeline 2.

It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Claims (4)

1. Wear the isolation supporting construction of highway tunnel foundation ditch of pipeline down, foundation ditch (1) is highway tunnel construction foundation ditch, wears existing pipeline (2) under foundation ditch (1), and the roof of highway tunnel (5) and the interval of pipeline (2) be greater than or equal to 0.5m, foundation ditch (1) region that pipeline (2) correspond is break zone (7), and it has subway tunnel (6), its characterized in that to violently wear in the below soil body of foundation ditch (1):

the isolation supporting structure comprises a pair of underground continuous walls (3) distributed along two side walls of the foundation pit (1), and the pair of underground continuous walls (3) are respectively disconnected in an interruption area (7); concrete supports (11) are arranged in the foundation pit (1) of the interruption area (7) corresponding to each pipeline (2), and the concrete supports (11) are arranged in parallel to the pipelines (2);

a pair of partition walls (4) are arranged between the pair of underground continuous walls (3), the pair of partition walls (4) are vertically arranged in the foundation pit (1) at intervals, the foundation pit (1) is divided into an isolation operation area (9) and an external operation area (10), the corresponding area of the foundation pit (1) between the pair of partition walls (4) is the isolation operation area (9), and the interruption area (7) is positioned in the middle of the isolation operation area (9);

an MJS gravity type retaining wall (14) is distributed on the side wall of the foundation pit (1) of the interruption area (7), and cast-in-place pile walls (13) are uniformly distributed along the outer side walls of a pair of continuous walls corresponding to the isolation operation area (9);

an MJS pit bottom reinforcing wall (12) is horizontally distributed at the bottom of a foundation pit (1) of the isolation operation area (9), and the thickness of the MJS pit bottom reinforcing wall (12) is more than or equal to 5 m; and the bottom of the foundation pit (1) of the external operation area (10) is horizontally provided with a rotary spraying pit bottom reinforcing wall (17) corresponding to the pair of partition walls (4), and the thickness of the rotary spraying pit bottom reinforcing wall (17) is more than or equal to 4 m.

2. The isolation support structure of a road tunnel foundation pit according to claim 1, wherein: the pair of underground continuous walls (3) are provided with folding walls (8) at the disconnected positions, the folding walls (8) are vertically connected with the ends of the continuous walls correspondingly, and the transverse extension length of each folding wall (8) is 1.0-1.5 m; the depth of the cast-in-place pile wall (13) is greater than that of the MJS gravity type retaining wall (14), and the pile bodies of the cast-in-place pile wall (13) are connected in a snap fit mode.

3. The isolation support structure of a road tunnel foundation pit according to claim 1, wherein: the transverse extension length of the MJS gravity type retaining wall (14) is more than 2 times of the longitudinal extension length of the interruption region (7), and the thickness of the MJS gravity type retaining wall (14) is more than the longitudinal extension length of the interruption region (7).

4. The isolation support structure of a road tunnel foundation pit according to claim 1, wherein: the concrete supports (11) are flush with the upper ends of the folding walls (8), concrete diagonal braces (15) are arranged between the side walls of the partition walls and the inner side walls of the corresponding continuous walls, and concrete cross braces (16) are arranged between a pair of continuous walls adjacent to the diagonal braces.

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