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Therefore, the Institute determined that the poor masonry quality of the retaining wall body constructed by the Water Corporation is the direct and fundamental cause of the collapse accident
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The mortar at the collapse site is basically no block, all of which are loose coarse sand, and the masonry mortar strength is too low and very not full
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3 work contact sheet, which is only “witness sampling and joint submission for inspection” Therefore, the court determined that the violations and omissions of the urban investment company were the important reasons for the collapse accident
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Therefore, the Institute believes that the original design defect of the design institute is the direct and important reason for the collapse accident
Water Corporation agrees to carry out construction in accordance with the white map submitted by urban investment company in violation of regulations
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In the objection letter, China National Water Resources Corporation said that “the bedrock of this section is red sandstone, which is easy to be weathered and softened under the action of water and air, which is easy to cause uneven settlement of the foundation, which may lead to cracking of the masonry retaining wall body, dumping along the cracking surface under the action of filling pressure..
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The mortar must be filled tightly, and the outer wall surface must be pointed with raw mortar
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Although Article 22 of the construction supervision contract of this case stipulates that the supervision company “shall report to the client when it finds that the design documents do not comply with relevant provisions or contract provisions”, considering that the construction supervision contract of this case clearly stipulates that the name of the supervision project is “construction supervision of Baojing County flood control project financed by ADB”, and the supervision stage is “supervision during construction”, Moreover, the urban investment company failed to prove that it had sent the construction design drawings (including the initial design and changed design) to the supervision company for review and issuance as required before delivering them to the water supply company
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In the judgment reasons part, the court of first instance found that the design institute violated the construction procedures and arbitrarily changed the design during the project construction, and the evidence was insufficient, so the court did not recognize it
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It also violates regulations and shall bear corresponding legal responsibilities
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Especially, the foundation part is filled and stacked
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Design requirements: the retaining wall structure adopts mortar block stone with mortar grade of M7.5, the compressive strength of the stone is not less than 30MPa, the block stone is roughly square, and the minimum thickness is not less than 25cm
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As a construction supervisor, the scope of responsibility advocated by the supervision company does not include the appeal reasons for supervising the design quality, which can be basically established
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The design institute reviews the left and right parts of the collapse section, and the construction quality of the reviewed part shall be basically consistent with that of the collapse section《 To a considerable extent, the review report indirectly proves that the opinion of the expert group can be established
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However, according to the investigation opinions of the expert group, part of the basement of the collapsed retaining wall is placed on the bedrock surface and is not embedded with the bedrock, resulting in sliding《 The expert group’s investigation Opinions also recorded that the design institute used the preliminary survey report as the basis for construction design
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It is certain that the urban investment company did not send the white drawings to the supervision company for filing and review before submitting them to the water supply company for construction according to this drawing, Therefore, the supervision company should not be deemed to have the obligation to review and issue the construction design drawings
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The design institute used the preliminary survey report as the basis for construction design, and did not design the embedding of retaining wall and bedrock, which obviously did not comply with relevant national regulations, leaving potential accidents of sliding and collapse
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What are the consequences of using the preliminary survey report as the basis for construction drawing design? Please look at this judgment case
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It should be considered that if there are no design defects in the original design structure drawing of the Design Institute, when repairing and rebuilding the collapsed section, it is only necessary to restore it according to the original design drawing, and there is no need to make major changes to the original design drawing
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The foundation surface of the retaining wall in the collapsed section fluctuates greatly, tends to the riverbed, and the foundation surface is seriously weathered, It is not located on the bearing stratum, does not meet the requirements of relevant specifications, and is inconsistent with the foundation level under design conditions“ It cannot be considered that this statement of the Water Corporation is entirely to evade responsibility, and some of its statements are in line with reality
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However, the supervision company failed to strictly require all the quality problems existing in the construction of the water head office to be seriously rectified, and certified and issued some projects with quality problems during measurement, so as to prevent collapse accidents as far as possible
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The actual construction situation is that the block stone size of the retaining wall in this section is too small, a large number of walls are not built with mortar, and the assembly method is chaotic
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Water Corporation refuses to comprehensively, timely and effectively rectify the construction quality problems pointed out by the supervision company, and even once resisted the supervision company to perform the supervision duties according to law and regulations, which should be considered as serious.
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Therefore, the Institute determined that the failure of some supervision companies to strictly adhere to the quality standards was an indirect and secondary reason for the failure to prevent the collapse accident
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The design institute appealed that it did not have the objective conditions and organizational ability to change the design at will, and it should be considered that the reason is basically tenable
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This is enough to prove that the original design structure drawing of the design institute has certain design defects
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As pointed out by the court of first instance, the urban investment company, as the construction unit, handed over the preliminary construction drawings (commonly known as white drawings) that had not been reviewed and signed and sealed by the design institute and designers to the water supply corporation and required them to carry out the construction according to this, which violated the basic construction procedure of the construction project; After the water head office and the supervision company report the problems found during the construction process, they do not actively deal with or reply, and only reply to the completely legitimate and necessary suggestion on parallel testing of materials, mortar and concrete test blocks proposed by the supervision company in [2008] No
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However, during the restoration and reconstruction of the collapsed retaining wall, the design institute changed the design scheme from the original balance weight retaining wall, with the bottom width of 7.6-8.4m, the balance platform width of 8.03-9.9m and the top width of 0.5m to widening and thickening on the basis of the original design section size, increased the height of the balance platform from 205m to 208.53m, changed the embankment top width to 1m, and changed the mortar strength from M7.5 to M10
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The state has corresponding regulations on the relevant procedures of design change
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Facts have proved that in order to speed up the construction period, the preliminary survey report is used as the design basis according to Party A’s requirements, and the responsibility lies with the designer《 The expert group’s appraisal opinions clearly pointed out: “after the on-site investigation of the collapsed retaining wall and the non collapsed retaining wall, the expert group believes that the retaining wall has the following problems: the main reason is that the masonry method of the retaining wall body seriously violates the requirements of the design drawings and construction specifications, and the masonry quality of the wall body is poor
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The poor masonry quality of the retaining wall body constructed by the Water Corporation is the direct and fundamental reason for the collapse accident
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The design institute also clearly pointed out in the review report: “the drainage pipes at many places of the wall body are not connected, which increases the water pressure behind the wall, which is extremely unfavorable to the stability of the wall body; At the same time, the block stone body of the wall body is too small, the mortar is not full, the masonry is not dense, there are many cavities, the wall structure is relatively loose and cannot be cemented as a whole, which is unfavorable to the shear and tensile strength of the wall body“ The Water Corporation did not explicitly deny the review report
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This significantly increases the section size of the retaining wall
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Due to the poor masonry quality of the wall body, the wall body does not have the ability to resist lateral pressure in case of slight external force, resulting in shear failure of the wall body and then overturning and collapse“ Although the Water Corporation disagreed with the expert group’s appraisal opinions and raised objections, it did not directly deny the opinions clearly put forward in the expert group’s appraisal opinions in the objection letter, but claimed that the collapse was caused by other reasons
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