How to calculate the top of bearing stratum of manual hole diggi

1. The construction is reasonable, but Party A is strong, sometimes it can only depend on the relationship ~ ~ ~

the extra part should not be reinforced, and the excavation strength should be smaller. A proper price should be adopted instead of a formal pile.

2. In my opinion, the bearing capacity of single pile can be checked according to rock socketed pile to meet the requirements of bearing capacity. If you are not at ease, do the static load test to meet the requirements of bearing capacity and deformation.

3. It is calculated by multiplying the bearing capacity of the final hole soil layer by the area of the hole bottom. Multiply it by a factor. The friction of pile is not included
it is the responsibility of geological exploration department to determine the value of bearing capacity characteristic value of bearing stratum at pile end, and it is the responsibility of structural designer to use it. If the bearing stratum of the pile is moderately weathered bedrock, core drilling sampling is allowed for testing. Core drilling sampling can take more samples or take all the important ones in the design, which is much more reliable than the probability of "one percent, no less than three for each project" in the static load method, and it saves time and effort

4. What is the height of empty hole
the depth of pile is calculated from the orifice to the elevation of bearing stratum

5. I don't understand
if weak interlayer is encountered at the designed depth of bearing stratum, excavation shall be continued. Until the stable rock stratum reaches the designed strength of bearing stratum. The depth of rock socketed (rock entry) is calculated from this point of view.

6. The allowable deviation of pile top elevation is - 50, + 30, and the allowable deviation of pile bottom is 0, + 300. Generally, the elevation of bearing stratum is not required. Generally, the depth into the bearing stratum is required, and the depth is only required

7. It is the responsibility of geological exploration department to determine the value of bearing capacity characteristic value of bearing stratum at pile end, and it is the responsibility of structural designer to use it. If the bearing stratum of the pile is moderately weathered bedrock, core drilling sampling is allowed for testing. Core drilling sampling can take more samples or take all the numbers that are considered very important in the design, which is much more reliable than the probability of "one percent, no less than three for each project" in the static load method. Moreover, it saves time and effort, does not cost people and money, and the site is more civilized.

8.

The rigidity angle between the manual digging pile and the pile is determined according to the imaginary rupture angle of the line between the pile bottom and the bearing stratum. If the bearing stratum has no definite imaginary rupture angle, it can be determined according to less than 45 degrees

in order to prevent the foundation section from being damaged by tension or shear, the maximum included angle between the inclined line and the plumb line from the bottom corner of the foundation to the wall or column side is the rigid angle. Once the included angle between the inclined line and the plumb line exceeds the rigid angle, the bending tensile stress and shear stress of the foundation section will exceed the strength limit of the foundation material and cause damage, Therefore, for the unreinforced spread foundation, it must meet the requirements of rigid angle

the width of the rigid foundation should be such that the bending tensile stress and shear stress of the foundation section under the action of the upper load do not exceed the strength limit of the foundation construction materials. If this requirement is satisfied, the maximum included angle between the vertical line of wall or column edge and the line of base edge is obtained, which is called rigid angle. The foundation limited by rigid angle is called rigid foundation

extended data:

in order to facilitate the organization of drainage in the manual hole digging pile well, a drain hole (the diameter of which is the same as the outer diameter of the water pipe) is reserved in the retaining wall of the permeable layer section, so as to facilitate the drainage of the connecting pipe, and it is blocked before the pouring of concrete, so as to ensure the verticality of the pile, It is required to check the pile center position and verticality once every three sections of retaining wall are poured

in addition to digging intercepting ditch around the pier and abutment on the surface, the water inside and outside the hole should be properly drained away from the pile hole. When pouring pile foundation concrete, if there is only a small amount of water seepage in several pile holes, measures should be taken to pour at the same time to avoid the difficulty of concentrating water in one hole. If the amount of porous seepage is large, which affects the quality of grouting, it is necessary to pump water in one hole

Network manual digging pile

Network rigid angle

9. How can there be a foundation without pile caps
how to calculate the specific quantities depends on how the subcontract is agreed
strictly speaking, there are two unit prices. One is the unit price of excavation, wall protection, reinforcement and concrete pouring; The other is directly heightening the retaining wall, without the unit price of excavation.

10. Before pouring concrete into the excavated pile, the reinforcement cage shall be placed first, and the thickness of the virtual soil in the hole shall be measured again. If the thickness exceeds the requirements, it shall be cleaned up. Appropriate measures shall be taken to prevent bending and distortion when carrying the reinforcement cage. When embedding the reinforcement cage, it shall be lifted straight, supported stably and sunk slowly at the hole position. When it is lowered to the design position, it shall be fixed immediately. The concrete cutting adopts the string cylinder, and the deep pile hole uses the concrete conit. If the groundwater is large, the concrete conit should be used to pour the concrete in the water. The concrete should be poured into the pile hole vertically to prevent the concrete from impacting the hole wall obliquely and causing collapse. The concrete shall be continuously poured in layers, and the pouring height of each layer shall not exceed 1.5m. For small diameter hole digging pile, the large slump and down impact of concrete are used to make it dense below 6m from the ground. Large diameter bored piles shall be tamped in layers. The first time, it is poured to the top surface of the bottom expanding part, then it is vibrated and compacted, and then the pile body is poured in layers until the pile top. Before the initial setting of concrete, it should be plastered and leveled to avoid plastic shrinkage cracks or circumferential dry shrinkage cracks. The floating slurry layer on the surface shall be chiseled to ensure the good connection with the upper bearing platform or bottom plate. The specification requirements of manual hole digging pile in Construction: the first section of well ring retaining wall shall meet the following requirements: the deviation between the center line of well ring and the design axis shall not be greater than 20 mm; The top surface of the well circle should be 150-200 mm higher than the site, and the wall thickness should be 100-150 mm higher than the wall thickness below; The thickness, tie bar, reinforcement and concrete strength of the wall should meet the design requirements; Generally, the removal of wall protection formwork should be carried out after 24 hours; When honeycomb and water leakage are found in the protective wall, reinforcement shall be made in time to prevent accidents; The overlapping length of the upper and lower sections of the retaining wall shall not be less than 50 mm; When pouring the concrete of pile body, it must pass through the chute; When the height is more than 3 meters, the tumbling barrel should be used. The height of the end of the tumbling barrel from the bottom of the hole should not be more than 2 meters, and the concrete should be compacted by the plug-in vibrator; When the seepage is too large, effective measures should be taken to ensure the pouring quality of concrete; The following safety measures should be taken for manual hole digging pile: emergency soft ladder must be set in the hole; The electric hoist and cage used are safe and reliable, and are equipped with automatic clamping safety device. It is not allowed to use hemp rope and nylon rope to hang or pedal the shaft wall flange up and down; Before starting work every day, it is necessary to detect the toxic and harmful gas in the underground, and there should be sufficient safety protection measures. When the excavation depth of pile hole exceeds 10 meters, there should be special equipment to supply air to the underground; Guardrail must be set around the orifice. 3、 In the process of construction quality control, the following situations often appear: 1. Prevention and control measures: there should be detailed geological report, especially hydrogeological report, so as to formulate effective measures in advance to rece the excess of virtual soil at the bottom of the hole. Strictly control the over excavation of the hole depth. After the hole is completed, all the empty soil at the bottom of the hole must be removed, and the solid undisturbed soil can be seen. Support measures should be taken when sand layer is encountered in the bottom expansion part. 2. The deviation of pile hole inclination and pile top displacement is large. In the process of construction, it should be located strictly according to the drawing, and there should be a re inspection system. The axial pile and pile position pile shall be distinguished by color and shall not be confused. Before starting to dig holes, it is necessary to use the ring made of positioning ring reinforcement to place the hole digging line, or position the gantry pile outside the pile position. When installing the wall protection formwork, the position of the formwork must be corrected with the pile center point, and the special person shall be responsible for it. The deviation between the center line of the positioning ring and the design axis shall not be greater than 20 mm. In the process of hole digging, the center line should be hung with a plumber at any time, and the deviation should be corrected immediately if the deviation is too large. It is required that the line should be suspended once for each supporting formwork (subject to the cross ring at the top center). When expanding the bottom, the center pile should be set out from the center point of the hole. The footage of annular excavation should be uniform, and the footage should be 100 mm around each time, so as to prevent wall collapse caused by excessive local excavation. After the completion of hole forming, the inspection and acceptance shall be carried out immediately, and the reinforcement cage shall be hoisted and placed immediately following the next process, and the concrete shall be poured to avoid unnecessary hole collapse caused by too long drying time, especially in rainy season or in case of water seepage. 3. Improper placing of reinforcement cage and pouring of concrete. After the hole completion acceptance, the reinforcement cage shall be hoisted immediately. If the elevation is not enough, the hole depth shall be measured, and the virtual soil and falling soil at the bottom of the hole shall be removed. The location of the lifting point should be selected for lifting the reinforcement cage. When lifting, the speed should be uniform and slow. If the long reinforcement cage is lifted, reinforcement measures should be taken to avoid deformation. When the cage is stuck, find out the cause, remove the fault and put it in normally. Before the reinforcement cage is hoisted, the over biased concrete retaining wall shall be treated to ensure the smooth hoisting of the reinforcement cage. The concrete mix proportion shall be calculated accurately to ensure the uniform slump. Before pouring concrete, the hole funnel should be placed and the virtual soil thickness in the hole should be measured again. When pouring the belled concrete, it should be poured to the top of the belled part for the first time, and then it should be vibrated tightly. Especially when pouring the concrete within 5m below the pile top, it should be vibrated while pouring, and the height of each pouring should not be more than 1.5m. When the seepage is too large, effective measures should be taken to ensure the pouring quality of concrete. The pouring of concrete shall be carried out continuously and not overnight. 4. Segregation of concrete in pile body. The treatment methods are as follows: (1) if the distance between the segregation position and the pile top is small, the upper concrete and the segregation layer shall be chiseled out and the concrete shall be poured again to connect the pile; ② If the segregation position is far away from the pile top, the air drill is used to drill vertically along the pile body, pass through the segregation layer, and then high pressure grouting is used to fill the space of the segregation layer. The premise of ensuring the quality of manual digging pile construction is to have a sound construction site quality assurance system. The quality of personnel should be high, the quality of materials should be guaranteed, the performance of construction machines and tools should be good, and various systems should be improved. 4、 In order to test the quality of pile body and whether the vertical ultimate bearing capacity of single pile meets the design requirements, according to the technical specification for testing of building foundation piles (JGJ106-2003), low strain pile body quality tests were carried out for all piles in the project, and three piles with a diameter of 800mm, a diameter of 1000mm without big end and a diameter of 1000mm with pile end expanded to 1200mm were selected, The vertical ultimate bearing capacity of single pile is tested. According to the test results, the vertical ultimate bearing capacity of single pile meets the design requirements. The quality of pile body is 86% for class I pile, 14% for class II pile and no class III pile. From the beginning of construction to the end of detection, wenxiangyuan pile foundation takes 65 days, which greatly shortens the construction period. The cost of manual digging cast-in-place pile is 750 yuan / m3, which saves investment and achieves good social and economic benefits.