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A. Digging, filling and repairing the channel foundation trench should be carried out according to the survey setting-out. Roots, silt, humic soil and dirt should be removed within the scope of the project. The height, size and smoothness of the channel foundation trench section should be strictly controlled. The deviation value should meet the requirements of the table below.
Permissible deviation value of construction section of cast-in-place seepage control canal
Permissible deviation of item (centimeter)
Canal bottom elevation (+2-3)
Channel Center Line (+2-3)
Canal bottom width (+3-5)
The width of the upper opening of the canal channel is (+4-8)
Flatness of Canal Bottom and Inner Slope (+2-3)
Note: Large and medium-sized channels should meet the requirements of high value, while small channels should meet the requirements of low value.
B. The cast-in-situ seepage control canal is laid out in accordance with the planning and structural dimensions. Mechanical or manual moulding is adopted. The size of the moulding is repaired by using large templates. The moulding is required to be compacted. The backfill should be compacted by layers with a thickness of no more than 20 cm and a dry bulk density of no less than 1.55 tons/cubic meter. Soil moulding should be poured as soon as possible. If it cannot be poured in time, it must be covered with plastic film to prevent damage to the model caused by wind, sunshine and rain.
C. During construction, raw materials should be sampled and inspected in stages and batches. The mix proportion of materials used should be checked at any time, and the construction procedures should be checked and accepted strictly. The weighing deviation values of various materials in construction are cement (+2%), yellow sand (+3%) and gravel (+3%).
D. Cast-in-place canal construction should be carried out in warm season. The construction of concrete with the daily average temperature below 5 C or the minimum temperature below - 3 C should be carried out in accordance with the requirements of SDJ207 - 82 in the low temperature season of the Code for Construction of Hydraulic Concrete. Construction should be stopped when the average daily temperature is below - 5 C.
E. Mixed concrete should be proportioned strictly in accordance with the design mix ratio and should not be altered without authorization. We should insist on weighing baskets by weighing them. We should not adopt the imprecise method of mixing only one baskets according to self-assessment. When concrete is mechanically mixed, the net mixing time should not be less than 2 minutes. When manual mixing is used, dry mixing should be done three times and wet mixing should be done three times. Only when the color is the same, can the concrete be used.
F. Casting concrete should be carried out continuously. Concrete should be mixed with mixing, such as segregation, serious bleeding, slurry leakage, collapse reduction and other problems, should be re-mixed in the pouring site, if more than the initial setting time of concrete, should be treated as waste. Coagulation time shall not exceed the stipulations in the table below.
Setting time of concrete labeled concrete (minutes)
Temperature below 25 and temperature above 25.
210 180 under 300 and 300
More than 300 180 150
G. The interval time of pouring concrete exceeding the initial setting time of concrete should be treated according to construction joints. The concrete surface of construction joints is chiseled and washed with water before continuing to pour. After wetting, a layer of 10-15mm cement mortar is laid on the surface. Its label and type of cement are the same as those of treated concrete.
H. In rainy season, it is not appropriate to pour concrete in the open air when it rains. After pouring, it should be covered in time to prevent rainwater from scouring newly poured concrete. The concrete should be covered and sprinkled within 12 hours after completion of pouring, and the dry and hard raw concrete should be covered immediately after completion of pouring and sprinkled to keep the surface wet. Maintenance date should not be less than 7 days and nights, slag cement and pozzolanic cement should not be less than 14 days and nights, and impermeable concrete should not be less than 14 days and nights.
I. During the construction of cast-in-situ seepage control canal, the concrete label should be greater than 150, the stone particle size should be less than 2 cm, and the water-cement ratio should be controlled within 0.6-0.65. The defects such as honeycomb, linen surface and so on, which occur locally in construction, should be repaired and restored by manual pressing board with cement mortar in time. The concrete is calendered once or twice. It is required that the surface of the retracted concrete channel should be smooth and smooth, and there should be no defects such as exposed stones and cracks.
