Many points involving cost can not be reflected in the drawings, and can only be found by going deep into the construction process. The lifting and reinforcement of the well pipe in the precipitation project is a hidden cost point. This paper uses cases to analyze the causes of the phenomenon, analyze the key points of the cost, and extend it to visa matters, and finally form the party**.
Background of the case
The second underground layer of a public building, the foundation pit is approximately rectangular, and the length of the east-west direction is about The maximum length of the north-south direction is about The maximum excavation depth Part of the dredging well inside the foundation pit, due to many factors, is set in the fertilizer groove, as shown in the figure. These factors may be the design positioning, or they may be adjustments to the hoistway position to avoid a component. Design description: "The detailed layout of each well location is determined according to the actual pay-off and construction on site, and the basic structure should be avoided and can be moved within the range".
Figure Drained well in a manure trough.
Produce phenomena
The on-site construction process is to drill wells first, and then excavate earthworks. In the process of earthwork excavation, the dry well located in the fertilizer trough has a gravel layer outside the pipe scattered and the pipe is exposed. Because of the meter-deep foundation pit, the sand-free pipe of the shaft has no way to support independently without reinforcement. It is necessary to remove the sand-free pipe first when the earthwork is excavated, and reinstall the reinforcement when the earthwork is backfilled, as shown in the figure. It is formed, the dredging well located in the fertilizer trough has one more process than other dredging wells: the secondary installation and reinforcement of the hoistway during backfilling, and the change of the groundwater level to determine the accompanying height of the gravel layer around the well pipe.
Figure Lifting and reinforcement when backfilling.
Cost points
1. See whether the precipitation cost in the contract is a lump sum use. This project is a financial investment, using the "Construction Engineering Bill of Quantities Valuation Specification" pricing, "Shandong Province Construction Engineering Consumption Quota" group price, precipitation belongs to the unit price measure fee project, apply the quota group price.
2. Look at the bidding group price and whether it includes the cost of secondary installation and reinforcement of the hoistway. "Shandong Province Construction Engineering Consumption Quota" in the large-diameter deep well precipitation drilling) sub-heading, the work content includes drilling rig drilling, sand less concrete well pipe, bottom and wall filling gravel, well washing, installation of waterproof pumps, test pumping; Precipitation pumping) includes pumping duty, shaft plugging, maintenance during use, and discharging water into open ditches. From the point of view of **, this fee is not taken into account. Objectively speaking, the quota level of the well drilling sub-project is relatively high, and the profit is larger. Therefore, some audits forcibly approve precipitation projects according to the market price, and do not follow the quota.
3. See if there is an agreement on this fee in the subcontract. There is no separate agreement for this project, and the general contractor arranges for precipitation subcontracting to do it, on the basis that this cost belongs to the maintenance of the hoistway. The unit price of this project is RMB and RMB per day of precipitation.
4. Whether there is a possibility of optimization of the original method. Original design method: the filter pipe adopts sand-free concrete water filter pipe, the outside of the pipe wall is backfilled with sand filter material, the backfill filter material adopts coarse gravel sand with a small uneven coefficient or the gravel with better rounding, and the water filter pipe joint is covered with a double-layer mesh filter screen, and bricks are laid along the wellhead and a manhole cover is arranged, as shown in the figure.
5. Carry out cost calculation. Analyze whether the optimized profit margin is higher than the current situation, and then consider whether it is convenient for construction. At the technical level, it is also necessary to comprehensively investigate the report and whether the on-site situation is feasible. The technology is feasible, the economy is reasonable, and the construction period is guaranteed, so that the change can be carried out through the management procedure. For example, some projects adopt the practice of management, as shown in the figure.
Figure Sample of the design of the dewatering well.
Figure Employing Pipeline Precipitation.
Extension of the main points
1. The cost of wellhead protection is attributed. The protective measures for tube wells in the process of earthwork excavation, as shown in the figure, are debatable about the attribution of the budget revenue. According to the "Code for Quantity Calculation of Housing Construction and Decoration Engineering" table safety civilization and other measures, the description of "completed project and equipment protection fee" is: the necessary protection measures such as covering, wrapping, sealing and isolation taken for completed projects and equipment. The focus of the dispute should be whether the temporary protection of the wellhead should be a "completed project and equipment protection fee".
Figure Temporary protective measures for dredging the wellhead.
For the downstream, whether this cost should be completed by the precipitation subcontracting team should be clearly written in the contract, otherwise there will be a rip-off.
2. Technical risk control. The reality is that many wells are filled in the process of earthwork excavation and become waste wells, as shown in the figure. At this time, it is necessary to pay attention to the control between the visa processing of budget income and the settlement of the team. It is also necessary to closely observe the technical risks arising from the reduction in the number of wells - the possibility of floor uplift due to the rise of water level, especially the weak links such as unsealed post-pouring belts. From the technical position, the well point must be protected in the process of earthwork excavation to avoid becoming an abandoned well, otherwise the cost will be lost due to small losses.
Figure The impact of earthwork excavation on the hoistway
3. Visa Matters 1. For the secondary installation and reinforcement of pipelines in the process of backfilling, they are not included in either the quota sub-item or the safe and civilized construction cost. It should be reported to the visa processing as appropriate. The point of contention is what caused the location of the dredged well in the fertilizer trough, and the explanation of the measure fee at the time of bidding.
4. Visa Matters 2. For the drain hose length of the pump. Quota subheading: Large-diameter deep well precipitation Precipitation pumping, each daily hose It can be seen that it does not refer to the drainage hose. The dredging well in the middle of the foundation pit is nearly 100 meters away from the drainage ditch around the foundation pit. During the actual construction, limited to the pump lift and drainage pipe damage, etc., it is necessary to discharge the well water that is too far away from the edge of the foundation pit to other wells near the foundation pit first, and then discharge the water from these wells, as shown in the figure. This increases the drainage burden on other wells, which may not be considered in the general design. Therefore, the hose fee is processed on a case-by-case basis.
Figure Drain hose arrangement.
Summary
Through the analysis of the case, it can be seen that the following methods can be used to solve a certain problem.
One is: look at the contract. Both upstream and downstream contracts depend on the billing scope, pricing mode, and calculation rules.
The second is: look at the first analysis. Straighten out the upstream and downstream, analyze the cost profit and loss, and determine the strategy.
The third is: look at the construction process. In-depth understanding of the construction process on site, and construction technology from the perspective of cost.
Fourth: look at the design drawings. Whether there is a possibility of optimization, and whether the changed approach is beneficial to all parties.
Fifth: look at the visa approval price. Determine the implementation strategy and report the visa approval price as appropriate.