ATLANTJET ANCHORS

A modification of the Atlant technology is its combination with jet grouting technology (jet-grouting) at a pressure of 20 MPa. To implement jet-grouting, the drill head is to be equipped with nozzles, and additional aluminum sealing elements are to be installed in the coupling joint.

The main advantage of this technology is a significant increase in the diameter of the anchor / pile compared to conventional injection technology.

Comparison of the technologies shows that if with the standard Atlant technology the pile diameter is usually 150-200 mm, then when using high pressures, the diameter is 400-700 mm.

The use of jet technology is justified in some cases. Such cases include the installation of piles in soft soils, when in order to ensure the bearing capacity it is necessary to increase the pile diameter, and for other tasks, when an increase in the pile diameter is necessary to ensure the intersection of piles, for example, when creating technological screens between pits under construction and closely spaced buildings, etc.

Ground anchors and piles according to the AtlantJET technology are to be installed during downward drilling to the design level with cement mortar supply W:C=1.0 at a pressure of 200 atm.

The cement mortar performs two functions. First, this mortar is a drilling mud that transports broken soil particles to the surface. Second, cement mortar is the primary injectable mortar that fills voids, cracks and impregnates the surrounding soil. That is why it is especially important that the solution to be constantly poured out of the wellhead during the drilling process, because the solution output to the surface guarantees the quality of the surrounding soil injection.

It should be noted, that it is possible to increase the diameter of the anchor root by varying the pressure of the cement mortar. Thus, it is advisable to increase the applied pressure during the installation of the anchor root in order to increase the soil bearing capacity.

Atlant JET ground anchors do not require pretensioning due to their high structural rigidity.

While installing the mounting point of Atlant JET screw anchor, it is enough to tighten the nut with a wrench with a tightening torque of 40-50 kgf∙m.

Fastening and testing of Atlant JET screw anchors should be carried out after curing of cement stone. The appropriate period is to be determined according to the composition of the cement solution. The recommended period is 28 days.

For calculations geotechnical structures a special MalininSoft software package is used.

MalininSoft software is designed specifically for calculating various types of underground structures: calculating the strength and stability of pit walls with anchors and spacers, calculating the stability of slopes, as well as calculating the settlement of pile-slab foundations.

MalininSoft official website http://malininsoft.ru/

«Subsoil. Verification of the safety of earthworks and foundation»

This method can be used for pre-calculation of anchors and piles by soil bearing capacity.

The standard was developed by the standards committee at the DIN (German Institute for Standardization), a registered society, as part of a unified German standard for structural engineering construction based on the concept of partial safety. The DIN 1054-2005 standard concerns the stability and suitability of buildings and structural elements in earthworks and in construction of bases and foundations. The standard also concerns the use and production of structural elements and includes modifications to existing buildings. This standard defines the limit state of soil, contains the main provisions and rules for its proper confirmation.

The soil bearing capacity of a self-drilling anchor is to be determined by the following formula:

Fd = π • D • lk • qsk

D = dскв • kd

where dскв – diameter of the well,

kd – coefficient of anchor root diameter increase,

lk – anchor root length,

qsk – resistance on the anchor side surface.

The recommended values for anchor root diameter increase and resistance on the anchor side surface are given in tables 1 and 2.

The optimal position of the anchor in the ground in accordance with the Kranz’s method is to be selected while calculating the stability of the “wall-soil-anchor” system for overturning around the bottom of the anchored wall, based on the condition that the soil shear strength in the system is overcome and a “deep slip line” is formed.

The “deep slip line” is to be taken as a straight line between the anchored wall turning point and the point c located in the middle of the anchoring length.

The design scheme for calculating the stability of the enclosing wall along the “deep slip line” is shown in the figure.

Constructed from the equilibrium condition of the shaded prism авсе the force polygon includes the weight of the soil G, the resultant of the active pressure Eа on the anchored structure, the reaction force RS, the bearing capacity of the anchor Ра and the resultant of the active pressure of the soil E’а on the fictitious anchor wall. The solution of the force polygon makes it possible to determine the horizontal projection Рах of the anchor bearing capacity, which brings the shaded prism to the state of ultimate stability.

Rollover stability coefficient Ку of the “wall-soil-anchor” system is to be determined from the relation Ky = Pax / Pwx ≥ γg