ATLANT ANCHORS

A distinctive feature of Atlant anchors is the combination of well drilling operation and anchor installation. The screw surface of tubular rods ensures reliable strength of anchor connection with the cement coating of its root part.

To roll screw surface on thick-walled pipes Two Roller Cold Rolling Machine is used. The process of profile rolling is carried out by rolling the outer surface of the pipe with knurling rollers during their simultaneous rotation and radial feed of one of them.

1 - drill bit depending on the type of soil and drilling method
2 - centralizer
3 - coupling
4 - sealing
5 - screw rod
6 - base plate
7 - spherical washer
8 - spherical nut

1.1. Anchors are to be installed by successive drilling of rods into the ground. The rods that make up the tie rod are built up using couplings while drilling. The first rod must be equipped with a drill bit.

1.2. Anchor rods are to be fed into the ground at a constant speed of not more than 0.5 m/min. and rotation about 50 rpm. For a drilling fluid is to be used a cement grout with a water-cement ratio W:C=1.0 (flushing), flushing pressure 0.5-1.5 MPa.

1.3. For water-cement grout is to be used portland cement of a grade not lower than PC400, GOST 10178-58 *.

1.4. Water used for preparation of the grout must meet the requirements of GOST 23732-79 and does not contain impurities that cause metal corrosion and prevent cement setting and hardening.

1.5. While drilling, it is necessary to monitor the filling of the well with flushing cement grout. Drilling is to be carried out only when there is output of drilling fluid and drilling cuttings out of the wellhead. When the fluid output stops, it is necessary to reduce the feed rate of the drill rods or to stop the feed of drilling rods without stopping rotation. After the drilling fluid output has resumed, it is necessary to resume the feeding of the rods.

1.6. Drilling of the rods and tightening of the couplings is to be carried out with the use of drilling rig and manual feeding of the rods.

1.7. For testing and fixing the structure, it is necessary to keep the last rod output from the wellhead.

2.1. After the calculated depth is reached while rotating of the drilling rod, a thick cement slurry with W: C = 0.4 is to be injected and displace the drill cuttings and insure the anchor ground bearing capacity.

2.2. The break between drilling and pressure testing should not exceed one hour, otherwise the drilling cuttings may thicken, it may not be completely displaced by a thick cement mortar from the wellhead and, accordingly, the solidity of the anchor body cement stone will be broken and the bearing capacity will decrease.

2.3. Injection of a thick cement slurry is to be carried out through the cavity of the rods and the drilling bit.

2.4. Well dynamic pressure testing is to be carried out with continuous rotation of the screw tie rod at a speed of 20-30 rpm, which ensures the rise of the cement slurry from the drill bit and its distribution without voids along the entire length of the embedment.

2.5. Pressure testing is to be carried out before the output of a thick cement slurry from the wellhead.

2.6. If there is no output of a thick cement slurry from the wellhead, it is necessary to repeat the pressure testing after 15-30 minutes through the hollow rod left in the well.

2.7. Consumption of cement mortar during dynamic pressure testing should be 50-60 liters per running meter of anchor depending on soils and bit diameter.

2.8. The drill rod is to be left in the well as an anchor tie rod.

3.1. Atlant ground anchors do not require pretensioning due to the high rigidity of the structure.

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

3.3. Fastening, as well as testing of Atlant screw anchors, is to be carried out after curing of cement stone. The appropriate period is determined according to the composition of the cement slurry. 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

ATLANT anchor systems brochure

Atlant Anchor Systems Organization Standard

NP RK 07-01.3-2011 Design and device for strengthening the base with vertical reinforcing elements

NTP RK 07-01.7-2012 Design of ground anchors